B-cell chronic lymphocytic leukaemia (B-CLL) cells display low amounts of surface immunoglobulins (sIg). To investigate the mechanisms underlying this phenomenon, we performed a thorough study of surface and intracellular expression of the B-cell receptor (BCR) components in B-CLL cells using flow cytometry. There was an heterogeneous pattern of expression. Overall, 20 of 22 samples showed reduced sIgM levels, compared with normal B cells. Among them, three (15%) had very low to undetectable intracellular IgM levels and variable amounts of CD79a and CD79b; nine (45%) had low intracellular CD79b levels but appreciable levels of IgM and CD79a; and eight (40%) had relatively normal intracellular levels of all BCR components. To investigate whether surface BCR levels could be controlled by the rate of CD79b synthesis, adenoviral vectors encoding CD79b were generated and used for gene transfer experiments. Delivery of CD79b to non-B cells transfected with IgM and CD79a lead to high-level expression of a functional BCR. Moreover, CD79b gene transfer in a B cell line derived from a B-CLL patient and characterised by low intracellular levels of endogenous CD79b consistently increased sIgM levels. These findings indicate that the phenotype of B-CLL cells in a subset of patients may depend primarily on poor CD79b expression, and suggest that upregulation of CD79b expression may correct the phenotype of these cells.

Plasmablastic lymphoma (PBL) is an aggressive malignancy that usually occurs in the setting of immunosuppression. The immunohistochemical profile of PBL is that of terminally differentiated B lymphocytes. CD138, CD38, and MUM1 are usually immunopositive. However, pan B-cell markers such as CD20 and PAX-5 are usually negative. MYC rearrangement is the most commonly encountered genetic alteration, with immunoglobulin (IG), especially immunoglobulin heavy (IGH) chain, being the most frequent partner. We report a case of PBL in a 48-year-old human immunodeficiency virus- (HIV-) positive male who was admitted to the hospital with signs and symptoms suspicious for tumor lysis syndrome. Bone marrow examination revealed hypercellular marrow with trilineage hypoplasia and sheets of intermediate to large neoplastic cells with basophilic vacuolated cytoplasm comprising the majority of cellular elements of the bone marrow. The neoplastic cells were negative for conventional B-cell, T-cell, plasma cell, and myeloid markers, while flow cytometric analysis revealed an abnormal CD45-dim population that was partially weakly positive for CD71 and CD79b. The diagnosis was initially thought to be a high-grade primitive hematopoietic neoplasm, possibly an acute undifferentiated leukemia. BOB-1, however, was immunopositive in the neoplastic cells, confirming its B-cell origin. MYC was positive by immunohistochemistry and break-apart FISH, as were CD45, MUM-1, and EMA immunostains. There was immunoglobulin kappa (IGK) light chain gene rearrangement by polymerase chain reaction (PCR). Additionally, Epstein-Barr virus- (EBV-) encoded small RNAs (EBER) were positive by in situ hybridization (ISH). The tumor proliferation index by Ki-67 immunostaining approached 95%. Although the tumor cells were negative for CD38 and CD138, the diagnosis of PBL was still rendered. We recommend using a broad spectrum of B-cell markers, including BOB-1 and OCT-2, in such challenging cases of B-cell lymphomas with no expression of conventional B-cell markers. We also emphasize that the negative CD38 and CD138 should not exclude PBL from the differential diagnosis.

Chronic lymphocytic leukemia is an extremely heterogeneous disease and prognostic factors such as chromosomal abnormalities are important predictors of time to first treatment and survival. Trisomy 12 is the second most frequent aberration detected by fluorescence in situ hybridization at the time of diagnosis (10-25%), and it confers an intermediate prognostic risk, with a median time to first treatment of 33 months and a median overall survival of 114 months. Here, we review the unique morphological, immunophenotypic, and genetic characteristics of patients with chronic lymphocytic leukemia and trisomy 12. These patients carry a significantly higher expression of CD19, CD22, CD20, CD79b, CD24, CD27, CD38, CD49d, sIgM, sIgk, and sIgλ and lower expression of CD43 compared with patients with normal karyotype. Circulating cells show increased expression of the integrins CD11b, CD18, CD29, and ITGB7, and of the adhesion molecule CD323. Patients with chronic lymphocytic leukemia and trisomy 12 frequently have unmutated IGHV, ZAP-70 positivity, and closely homologous stereotyped B-cell receptors. They rarely show TP53 mutations but frequently have NOTCH1 mutations, which can be identified in up to 40% of those with a rapidly progressive clinical course.

Postweaning multisystemic wasting syndrome (PMWS) is one of the pig diseases with major economic impact worldwide. Clinical, pathologic and some immunologic aspects of this disease are relatively well-known, but the molecular mechanisms underlying the pathogenic mechanisms of the disease are still poorly understood. The objective of the present study was to investigate the global transcriptome changes in the mediastinal lymph nodes from pigs naturally affected by PMWS, as well as healthy counterparts, using the Affymetrix Porcine Genechip(®). From 366 transcripts showing significant differential abundance in the PMWS group of pigs relative to healthy animals, 229 showed higher and 137 lower abundance. A relative increased abundance of mRNAs coded by a large set of genes involved in the inflammatory responses (e.g. cytokines, acute phase proteins, and respiratory burst) was observed in PMWS affected pigs. The Gpnmb and Lgals3 genes, which have antagonistic functions in regulation of inflammatory processes, showed high mRNA levels in diseased pigs. The complement system was altered by PMWS, notably by the lower levels of Cr1 mRNA, which might favour both complement deposition and secondary infections by impairing phagocytosis. Decreased mRNA abundance of several genes involved in lymphocyte activation/differentiation, such as Cd79b, Cd19, Cd21 and MybL1, and the high level of Vsig4 mRNA, which can compromise the activation of residing T-cells, pointed towards a defective adaptive immunity. This is the first study on gene expression in pigs naturally affected by PMWS. The present results allowed identifying potential mechanisms underlying the inflammation and lymphocyte depletion in lymphoid tissues by complement mediated damage and immunosuppression, which are key features of PMWS.

CD79, composed of two distinct chains called CD79a and CD79b, is a transmembrane protein that forms a B cell antigen receptor with membrane immunoglobulin, and generates a signal following antigen recognition by the B cell receptor. In this study, the CD79a (OnCD79a) and CD79b (OnCD79b) were cloned and identified from Nile tilapia (Oreochromis niloticus). The cDNA of ORF for OnCD79a and OnCD79b are 669 and 627 bp, coding 222 and 208 amino acids, respectively. The deduced protein analysis showed that both CD79a andCD79b contain an immunoreceptor tyrosine-based activation motif in their intracellular tails that used to propagate a signal in a B cell. Expression analysis revealed that both CD79a and CD79b expressed at high levels in immune tissues, such as anterior kidney and spleen, and in IgM⁺ B cells. Upon Streptococcus agalactiae (S. agalactiae) infection, the expressions of OnCD79a and OnCD79b were significantly up-regulated in anterior kidney and spleen. The significant up-regulations of OnCD79a and OnCD79b were also detected in leukocytes after in vitro challenge with S. agalactiae. Further, stimulations of LPS and anti-OnIgM monoclonal antibody induced significant up-regulations of OnCD79a and OnCD79b in leukocytes. Taken together, the results of this study indicated that CD79 molecule, playing roles in BCR signaling, was likely to get involved in host defense against bacterial infection in Nile tilapia.

Interleukin-2 receptor subunit beta of flounder (Paralichthys olivace, fIL-2Rβ) was annotated on the NCBI, its gene was cloned and characterized functionally in this study. And then the amino acids sequences and tertiary structure of fIL-2Rβ were analyzed, respectively. RT-PCR and ImageJ analyzed showed that fIL-2Rβ mRNA were expressed in the gill, spleen, kidney, intestines, liver, blood, muscle and skin, which showed high signals in spleen and blood. And then the recombinant protein of fIL-2Rβ extracellular region and its polyclonal antibodies were produced, native fIL-2Rβ molecules in flounder peripheral blood leukocytes (PBLs) were identified at 60.7 kDa by Mass spectrometry, which were in accordance with the molecular mass of full fIL-2Rβ protein calculated on the predicted protein sequence. Then the IL-2Rβ+ cell in T/B lymphocytes were characterized by Flow cytometry and indirect immunofluorescence assay, respectively. The results showed that the percentages of IL-2Rβ+ leukocytes, IL-2Rβ+/CD4+, IL-2Rβ+/IgM+ lymphocytes were 18.4 ± 2.7%, 4.5 ± 0.8%, 4.3% ± 0.5 in PBLs, and were 13.6 ± 0.9%, 4.6 ± 1.1%, 6.1% ± 0.4 in spleen, similarly, the percentages of IL-2Rβ+ leukocytes, IL-2Rβ+/CD4+, IL-2Rβ+/IgM+ lymphocytes were 9.4 ± 0.3%, 4.0 ± 0.5%, 5.7 ± 0.1% in head kidney, respectively. After KLH injection, compared with control group, the gene expression of IL-2, IL-2Rβ, CD3, TCR, CD79b and IgM in spleen of flounder were up-regulated, respectively (p < 0.05). And the FCM results showed that the percentages of IL-2Rβ+ leukocytes in PBLs were significantly increased post Keyhole limpet hemocyanin (KLH) injection, which peaked 23.9 ± 0.9% at 9^th day (p < 0.05). To our knowledge, those results first reported that the characteristics of IL-2R and IL-2R + molecules were expressed on both B and T lymphocytes in fish. At the same time, this study lays a foundation for further exploring the interaction between IL-2 and IL-2R to promote cell proliferation and carrying out biological functions.

Meningeal lymphomatosis (ML) as the first manifestation of a splenic marginal zone lymphoma (SMZL) is rare. The descriptions of only 2 cases with this complication, one of which had ML as the first manifestation, have been published to date. We describe a 53-year-old man, an ex-smoker, who presented with transitory episodes of bilateral loss of visual acuity. On examination, only papilledema and splenomegalia were observed. The hemogram showed a predominance of lymphocytes with a villous morphology. Cytochemical staining and an immunophenotypic analysis revealed a positive reaction to tartrate-sensitive acid phosphatase and B-lineage markers (CD19+, CD20+, CD79b+, surface immunoglobulin 3 expression, immunoglobulin D+, CD5-, CD23-, CD10-, CD25-, CD103-, and CD11c-). Magnetic resonance imaging of the brain showed tumoral infiltration in both optic nerves and in the cervicodorsal meninges. The cerebrospinal fluid examination revealed significant pleocytosis, and all lymphocytes had a phenotype identical to that of the peripheral blood, confirming the presence of ML. The bone marrow section also showed lymphocytes with an immunophenotype identical to that of the peripheral blood.A splenectomy confirmed the SMZL diagnosis. Treatment with corticosteroids and intrathecal chemotherapy was administrated; however, the response was not good, and the patient died. In this report, we discuss the other 2 cases and ML in B-cell chronic lymphoproliferative disorders.

BACKGROUND

Cell therapy has been promising for various diseases. We investigated whether transplantation of human umbilical cord mesenchymal stem cells (hUCMSCs) has any therapeutic effects on D-galactosamine/lipopolysaccharide (GalN/LPS)-induced fulminant hepatic failure in mice.

METHODS

hUCMSCs isolated from human umbilical cord were cultured and transplanted via the tail vein into severe combined immune deficiency mice with GalN/LPS-induced fulminant hepatic failure. After transplantation, the localization and differentiation of hUCMSCs in the injured livers were investigated by immunohistochemical and genetic analyses. The recovery of the injured livers was evaluated histologically. The survival rate of experimental animals was analyzed by the Kaplan-Meier method and log-rank test.

RESULTS

hUCMSCs expressed high levels of CD29, CD73, CD13, CD105 and CD90, but did not express CD31, CD79b, CD133, CD34, and CD45. Cultured hUCMSCs displayed adipogenic and osteogenic differentiation potential. Hematoxylin and eosin staining revealed that transplantation of hUCMSCs reduced hepatic necrosis and promoted liver regeneration. Transplantation of hUCMSCs prolonged the survival rate of mice with fulminant hepatic failure. Polymerase chain reaction for human alu sequences showed the presence of human cells in mouse livers. Positive staining for human albumin, human alpha-fetoprotein and human cytokeratin 18 suggested the formation of hUCMSCs-derived hepatocyte-like cells in vivo.

CONCLUSIONS

hUCMSC was a potential candidate for stem cell based therapies. After transplantation, hUCMSCs partially repaired hepatic damage induced by GalN/LPS in mice. hUCMSCs engrafted into the injured liver and differentiated into hepatocyte-like cells.

OBJECTIVE

The European Research Initiative on chronic lymphocytic leukemia (ERIC) has designed a single-tube, 8-color chronic lymphocytic leukemia CLL-MRD flow cytometric assay to standardize testing in patients with B-CLL. This study aims to optimize and validate the 8-color CLL-MRD assay, with the desired outcome of it being implemented in St. James's Hospital Dublin and potentially other hospitals worldwide as the most accurate flow-based B-CLL-MRD detection currently available.

METHODS

The single-tube assay incorporates 8 antibodies, namely, CD5, CD3, CD19, CD20, CD22, CD43, CD79b, and CD81. We tested a combination of 52 peripheral blood and bone marrow specimens with the antibodies to develop a sequential gating strategy that uses the typical phenotype of B-CLL cells to enumerate small residual B-CLL populations after treatment, effectively distinguishing them from the normal polyclonal and regenerating B-cells. We performed sensitivity assays via a set of serial dilutions and compared the assay with the current International Standardized Approach (ISA) method currently in use for MRD testing in B-CLL.

RESULTS

The 52 specimens that we analyzed displayed MRD levels from 0.004% through 78.000%. Dilutional studies demonstrated detection of disease to a level of 0.00702%, and an excellent correlation was achieved against the current ISA method (R(2)= 0.991).

CONCLUSIONS

The 8-color CLL-MRD assay provides a more informative approach than its predecessors for the assessment of MRD in B-CLL by functioning as an important disease biomarker, with MRD negativity acting as an indicator to achieving a clinical endpoint.

CD200, a transmembrane type Ia glycoprotein belonging to the immunoglobulin superfamily, has been shown to have a differential expression in B-cell neoplasms. Here, we retrospectively assessed the diagnostic relevance of CD200 on 427 patients with B-cell chronic neoplasms in leukemic phase (median age, 69 y; range, 35-97 y). The final diagnosis based on the investigator's assessment was chronic lymphocytic leukaemia (CLL) in 75% of cases and non-CLL in 25% of cases. Sensitivity and specificity for the diagnosis of CLL (vs non-CLL) were calculated for the following markers: CD200, CD5, CD22, CD23, CD79b, FMC7, and SmIg. CD23 was the only marker without a statistically significant difference between the investigator assessment and the flowcytometric analysis. The other markers were unable-when individually evaluated-to discriminate between CLL and non-CLL, requiring the integration into a scoring system. The modified score no. 1 (addition of CD200) showed superimposable sensitivity and specificity compared with the Matutes score. The substitution of CD79b (modified score no. 2), surface membrane immunoglobulins (SmIg) (modified score no. 3), and CD79b and FMC7 (modified score no. 4) with CD200 showed that only the modified score no. 4 had both higher sensitivity and higher specificity compared with standard Matutes score. In conclusion, this work defines a simplified score, compared with the classical Matutes score, for the differential diagnosis of chronic B-cell leukaemia-which only requires 4 markers instead of 5 (CD5, CD23, CD200, and SmIg).

BACKGROUND

Primary mediastinal large B-cell lymphoma (PMBL) is a distinct subtype of diffuse large B-cell lymphoma (DLBCL) frequently observed in young patients. High-dose immunochemotherapy constitutes the current therapeutic gold-standard, despite significant toxicity and serious late effects. Several hotspots harboring oncogenic gain-of-function mutations were recently shown to pose vital hallmarks in activated B-cell like (ABC-) (CD79B, CARD11 and MYD88) and germinal center like (GCB-) DLBCL (EZH2), respectively. Several promising targeted-therapy approaches, derived from these findings, are currently under development.

METHODS

We thoroughly characterized a cohort of 25 untreated patients with de novo PMBL by immunohistochemical and cytogenetic means and assessed the prevalence of activating mutations affecting EZH2, CD79B and CARD11 utilizing a polymerase chain reaction (PCR)-based capillary sequencing approach. Moreover, the MYD88 p. L265P status was assessed by employing a pyrosequencing approach.

RESULTS

PMBLs included in this study did not harbor any of the reported hotspot mutations activating the nuclear factor (NF)-kappa B signaling cascade or the EZH2-mediated epigenetic deregulation of gene expression. Immunohistochemical characterization revealed an ABC phenotype in 44% (n=11) of cases.

CONCLUSIONS

We report that genetic alterations of these genes are rare events in PMBL unlike other subtypes of DLBCL. Our findings suggest that a substantial subset of PMBL patients may benefit from treatment approaches targeting BCR-mediated activation of NF-kappa B.

BACKGROUND

Numerous genomic abnormalities in B-cell non-Hodgkin lymphomas (NHLs) have been revealed by novel high-throughput technologies, including recurrent mutations in EZH2 (enhancer of zeste homolog 2) and CD79B (B cell antigen receptor complex-associated protein beta chain) genes. This study sought to determine the evolution of the mutational status of EZH2 and CD79B over time in different samples from the same patient in a cohort of B-cell NHLs, through use of a customized multiplex mutation assay.

METHODS

DNA that was extracted from cytological material stored on FTA cards as well as from additional specimens, including archived frozen and formalin-fixed histological specimens, archived stained smears, and cytospin preparations, were submitted to a multiplex mutation assay specifically designed for the detection of point mutations involving EZH2 and CD79B, using MassARRAY spectrometry followed by Sanger sequencing.

RESULTS

All 121 samples from 80 B-cell NHL cases were successfully analyzed. Mutations in EZH2 (Y646) and CD79B (Y196) were detected in 13.2% and 8% of the samples, respectively, almost exclusively in follicular lymphomas and diffuse large B-cell lymphomas. In one-third of the positive cases, a wild type was detected in a different sample from the same patient during follow-up.

CONCLUSIONS

Testing multiple minimal tissue samples using a high-throughput multiplex platform exponentially increases tissue availability for molecular analysis and might facilitate future studies of tumor progression and the related molecular events. Mutational status of EZH2 and CD79B may vary in B-cell NHL samples over time and support the concept that individualized therapy should be based on molecular findings at the time of treatment, rather than on results obtained from previous specimens. Cancer (Cancer Cytopathol) 2013;121:377-386. © 2013 American Cancer Society.

OBJECTIVE

To determine whether the immunoglobulin V(H) gene mutational status has an effect on the activation, proliferation and surface antigen expression of chronic lymphocytic leukemia (CLL) cells when stimulated in vitro.

METHODS

The proliferation and activation responses of CLL cells were studied in 22-immunoglobulin gene V(H) unmutated (UM-CLL) and 12 hypermutated (M-CLL) CLL cases in 4-day cultures. As the mitogen responses have been previously shown to be diverse in CLL, a case-specific strategy based on optimized mitogen combinations (OMCs) of interleukin-2 (IL-2), 12-O-tetradecanoylphorbol 13-acetate (TPA), Staphylococcus aureus Cowan 1 (SAC), and human recombinant tumor necrosis factor alpha (TNF) was applied in cell stimulation. The expression of 23 surface membrane antigens (CD5, CD11c, CD19, CD20, CD21, CD22, CD23, CD25, CD27, CD38, CD40, CD45, CD45RA, CD45RO, CD79b, CD80, CD95, CD124, CD126, CD130, FMC7, IgD, and IgM) was studied by flow cytometry at days 0 and 4.

RESULTS

The proliferation and activation responses were similar in UM-CLL and M-CLL when OMCs contained IL-2, TPA or TNF. SAC induced faster proliferation in UM-CLL than in M-CLL. OMC stimulation induced preferential down-regulation of growth- promoting cell surface receptors CD5, CD21, and CD124 and preferential up-regulation of growth-inhibiting antigen CD80 in M-CLL.

CONCLUSIONS

Difference in immunophenotypic evolution of UM-CLL and M-CLL can be demonstrated if appropriate matrix signals are provided. The pathways for CD5, CD21, CD124 (IL4R), and CD80 (B7-1) regulation should be further explored in relation with somatic hypermutation and outcome of CLL.

BACKGROUND

Chronic lymphoproliferative disorders (CLD) are frequently found in patients with hepatitis viral infections, which can lead to changes in pathogenesis. Hepatitis viruses are hepatotrope viruses, potentially lymphotrope and also potentially oncogenic (hepatocellular carcinoma) viruses. HBV and HCV are involved in autoimmune disorders and in the ethiopathogeny of chronic lymphoproliferative disorders.

OBJECTIVE

Detection of immunophenotype changes of malignant lymphocytes in CLD--especially CLL--associated with hepatitis viral infections.

METHODS

Bone marrow aspirate, peripheral blood samples on EDTA were available for analysis from 58 patients from a follow-up schedule of the Department of Hematology SUUB from March 2008 until June 2009. The patients were diagnosed with chronic lymphoproliferative disorders associated with hepatitis virus B/C/D infections. A group of 28 consecutive unselected patients with CLL who met the diagnostic criteria of the National Cancer Institute-Working Group (NCI NCIWG), and associated hepatitis viral infection (v-CLL) were studied for the expression of several immunophenotypical markers, in comparison to CLL patients without viral infection (control group). Immunophenotyping analysis was performed on a FACS Calibur flowcytometer with a large panel according to EGIL/WHO recommendations. The diagnosis was completed after the histological and immunochemical analysis from tumoral lesions.

RESULTS

Demographics characteristics--male/female ratio 1/2, average age 64 years. Disease type: 90% B-CLD, 5% T-CLD, 5% Hodgkin's disease. The viral infections: 58.53% HCV, 34.41% HBV, 2.43% HBV+HDV, 2.43% HCV+HDV, 2.43% HBV+HCV+HDV. We found in CLL with viral coinfection (v-CLL) cases an elevated expression of B-cell markers--CD19 (Md95/92), CD20 (Md 90/39), CD79b (Md58/31), CD23 (Md67/37). Poor prognosis markers have a higher expression in v-CLL: CD38 (Md49/24), Bcl2 (Md 46/5), cyclin D19 (Md 11/0.5). No change in ZAP-70 expression was observed: Md 59.5/59.1.

CONCLUSIONS

Hepatitis viruses could be involved in the pathogenesis of CLD, but as a trigger for a more aggressive outcome. Higher expression of B-cell markers CD19, CD20 in CLL with viral infection suggests a change to atypical CLL, sustained by elevated expression of known poor prognosis markers bcl-2, cyclin D1 and CD38. Lack of ZAP-70 expression could be explained by a strong correlation with a basic unmutated IgVH status, not related to the viral infection. We found a higher frequency of HCV infection in patients with CLD and especially in CLL patients, which were analyzed extensively for immunophenotypical changes. In the present study, we demonstrated that this CD5+ B cell population with clonal expansion, defining CLL patients, has a different immunophenotype, probably related to the hepatitis viral infection.

Epstein-Barr virus-positive mucocutaneous ulcer (EBVMCU) is a newly recognized provisional entity included in mature B-cell neoplasm in the latest 2016 World Health Organization Classification. It has a self-limited growth potential with a high predilection for oral cavities and occurs in age-related or iatrogenic immunodeficiency with indolent clinical courses. However, it shares histological features with EBV-positive diffuse large B-cell lymphoma (DLBCL), and this often leads to diagnostic challenges and controversies in patients with an oral EBV-positive B-cell neoplasm. The aim of this study was to better characterize and comprehend the pathophysiology of DLBCL and EBVMCU in the oral cavity. We conducted clinicopathologic and recurrent gene mutation analysis of 49 cases (14 EBV positive, 35 EBV negative), including cases diagnosed as DLBCL or B-cell lymphoproliferative disorders with high-grade morphology in the oral cavity. All EBV-positive cases matched the criteria of EBVMCU, with significantly earlier clinical stages than the EBV-negative group (P=.0006). Besides, histological analysis showed that all EBV-positive cases presented polymorphous features, whereas 91.4% (32/35) of the EBV-negative cases showed diffuse and monotonous proliferation (P<.0001). Furthermore, EBV-positive cases presented favorable clinical outcomes without disease-related death or recurrence. Gene mutation analysis (MYD88, CD79A, CD79B, CARD11, and EZH2) revealed that 33.3% (9/27) of EBV-negative cases harbored at least 1 gene mutation, whereas no gene mutation was observed in the EBV-positive group (0/11). These results suggest that oral EBV-positive B-cell lymphoid proliferation with polymorphous features often fulfill the criteria for EBVMCU, with clinicopathologically and genetically distinctive properties.

In the region between the polyadenylation site of the rat skeletal muscle (SkM) Na-channel gene and the 5' end of the growth hormone (GH) gene, a gene coding for B-cell-specific membrane protein B29/Ig-beta was found and noted to have the same orientation as the Na-channel and GH genes. Rat B29/Ig-beta gene was 3.1 kb in length with six exons and was separated by 3.3 and 9.3 kb from Na-channel and GH genes, respectively. Rat B29/Ig-beta protein comprised 228 amino acids, and its amino acid sequence was 85 and 69% identical with the mouse and human counterparts, respectively. With the long-area PCR method, genomic DNA connecting human SkM Na-channel (SCN4A) and B29/Ig-beta (CD79B) genes and CD79B and GH (GH1) genes was amplified, and the physical linkage of SCN4A/CD79B/ GH1 genes in the human genome was established. The human CD79B gene was separated by 6.3 and 10.5 kb from the SCN4A and GH1 genes, respectively.

The goal of this study was to evaluate routine flow cytometric (FC) immunophenotypic markers in differentiating between Burkitt lymphoma (BL) and CD10+ diffuse large B-cell lymphoma (DLBCL). We performed retrospective analysis of FC data from 55 patients. We evaluated 9 FC parameters: forward and side scatter (FSC and SSC); mean fluorescent intensity (MFI) for CD20, CD10, CD38, CD79b, CD43, and CD71; and the percentage of neoplastic cells positive for CD71 (%CD71). The FSC; MFIs of CD10, CD43, CD79b, and CD71; and %CD71 cells were significantly different between BL and CD10+ DLBCL (P < .05; Student t test). A 5-point scoring system (FSC, %CD71, and MFIs of CD43, CD79b, and CD71) was devised, and 6 (60%) of 10 BLs scored 3 or greater and 1 (10%) of 10 CD10+ DLBCLs scored 3 (P = .04; χ(2)). Our findings indicate that routine FC parameters can aid in differentiating BL from CD10+ DLBCL.

CD79a and CD79b heterodimers are the important signaling components of B cell receptor (BCR) complex which plays a crucial role in B cell development and antibody production. In the present study, CD79a and CD79b homologues from Chinese sucker (Myxocyprinus asiaticus), namely MaCD79a and MaCD79b, were identified and their expression at early developmental stages and under constitutive and stimulated conditions were investigated. The cDNA sequences for MaCD79a and MaCD79b contained open reading frame of 678 and 636 bp in length for 225 and 211 amino acid residues, respectively. The conserved features and important functional residues were found by sequence analysis. RT-PCR analysis revealed that transcripts of MaCD79s were detected in eggs and hatchling at 1-3 and 5-11 days post hatching (dph), but not detected at 13-17 and 19-27 dph, and constantly detected from 30 dph. Tissue distribution analysis showed that MaCD79s was most highly expressed in immune tissues, such as the spleen, head kidney, and kidney; the relatively low levels were detected in the heart, gill, and liver. Results of in situ hybridization also confirmed that MaCD79s is mainly expressed in systematic immune organs. Meanwhile, similar to IgM, MaCD79s-expressing cells in mucosal immune organ including the digestive track and gill were observed. Additionally, significant upregulation of MaCD79s was seen in the head kidney and spleen of Chinese sucker injected with Aeromonas hydrophila by quantitative real-time PCR. Taken together, our findings provided further information regarding fish CD79s gene and its role in adaptive immunity, which will contribute to the preservation and aquaculture of Chinese sucker.

Teleost B cells have phagocytic activities for ingesting particulate antigens, such as bacteria, in addition to the functional secretion of immunoglobulins (Igs). In the present study, the phagocytic activities of IgM⁺ B cells under various differentiational conditions residing in peripheral blood leukocytes were investigated in a teleost fish Nile tilapia (Oreochromis niloticus). The IgM⁺ B cells were recognized as IgM^lo or IgM^hi subsets based on their membrane IgM (mIgM) levels. The mIgM, secreted IgM (sIgM), major histocompatibility complex class II and reactive oxygen species were detected. Expressions of transcription factors (Pax5 and Blimp-1) and B cell signaling molecules (CD79a, CD79b, BLNK, and LYN) suggested that IgM^lo B cells were resembling as plasma-like cells and IgM^hi resembling as naïve/mature B cells, respectively. Analysis of phagocytic activities demonstrated that both IgM^lo and IgM^hi B cells have a similar phagocytic ability (phagocytosis percentage); however, the phagocytic capacity [phagocytic index and the mean fluorescence intensity (MFI)] of IgM^hi B cells was significantly higher than that of IgM^lo B cells. Taken together, the results indicated that B cell differentiation may cause the decrease of phagocytic capacity but not phagocytic ability of phagocytic IgM⁺ B cells in teleost. The finding may provide an evolutionary evidence for understanding the greater specialization of the B cell in more sophisticated adaptive humoral immunity, by decreasing phagocytic activity in order to contribute its function more specifically into antibody-secreting.

Current understanding of the mutation spectrum of relapsed/refractory (RR) tumors is limited. We performed whole exome sequencing (WES) on 47 diffuse large B cell lymphoma (DLBCL) tumors that persisted after R-CHOP treatment, 8 matched to primary biopsies. We compared genomic alterations from the RR cohort against two treatment-naïve DLBCL cohorts (n=112). While the overall number and types of mutations did not differ significantly, we identified frequency changes in DLBCL driver genes. The overall frequency of MYD88 mutant samples increased (12% to 19%), but we noted a decrease in p.L265P (8% to 4%) and increase in p.S219C mutations (2% to 6%). CARD11 p.D230N, PIM1 p.K115N and CD79B p.Y196C mutations were not observed in the RR cohort, although these mutations were prominent in the primary DLBCL samples. We observed an increase in BCL2 mutations (21% to 38% of samples), BCL2 amplifications (3% to 6% of samples) and CREBBP mutations (31% to 42% of samples) in the RR cohort, supported by acquisition of mutations in these genes in relapsed compared to diagnostic biopsies from the same patient. These increases may reflect the genetic characteristics of R-CHOP RR tumors expected to be enriched for during clinical trial enrollment. These findings hold significance for a number of emerging targeted therapies aligned to genetic targets and biomarkers in DLBCL, reinforcing the importance of time-of-treatment biomarker screening during DLBCL therapy selection.

A relatively large repertoire of type I interferon (IFN) genes is apparent in rainbow trout/Atlantic salmon, that includes six different IFN subgroups (IFNa-IFNf) belonging to the three known type I IFN groups (1-3) in bony fish. Whether this is true for other salmonids, and how the various type I subgroups evolved in teleost fish was studied using the extensive genomic resources available for fish. This confirmed that salmonids, at least the Salmoninae, indeed have a complex (in terms of IFN subgroups present) and large (number of genes) IFN repertoire relative to other teleost fish. This is in part a consequence of the salmonid 4R WGD that duplicated the growth hormone (GH) locus in which type I IFNs are generally located. Divergence of the IFN genes at the two GH loci was apparent but was not seen in common carp, a species that also underwent an independent 4R WGD. However, expansion of IFN gene number can be found at the CD79b locus of some perciform fish (both freshwater and marine), with expansion of the IFNd gene repertoire. Curiously the primordial gene order of GH-IFNc-IFNb-IFNa-IFNe is largely retained in many teleost lineages and likely reflects the tandem duplications that are taking place to increase IFN gene number. With respect to the evolution of the IFN subgroups, a complex acquisition and/or loss has occurred in different teleost lineages, with complete loss of IFN genes at the GH or CD79b locus in some species, and reduction to a single IFN subgroup in others. It becomes clear that there are many variations to be discovered regarding the mechanisms by which fish elicit protective (antiviral) immune responses.

In diffuse large B cell lymphoma (DLBCL), tumors belonging to the ABC but not GCB gene expression subgroup rely upon chronic active B cell receptor signaling for viability, a dependency that is targetable by ibrutinib. A phase III trial ("Phoenix;" ClinicalTrials.gov: NCT01855750) showed a survival benefit of ibrutinib addition to R-CHOP chemotherapy in younger patients with non-GCB DLBCL, but the molecular basis for this benefit was unclear. Analysis of biopsies from Phoenix trial patients revealed three previously characterized genetic subtypes of DLBCL: MCD, BN2, and N1. The 3-year event-free survival of younger patients (age ≤60 years) treated with ibrutinib plus R-CHOP was 100% in the MCD and N1 subtypes while the survival of patients with these subtypes treated with R-CHOP alone was significantly inferior (42.9% and 50%, respectively). This work provides a mechanistic understanding of the benefit of ibrutinib addition to chemotherapy, supporting its use in younger patients with non-GCB DLBCL.

Keywords: ABC DLBCL; BTK inhibitor; CD79B; MYD88; NOTCH1; cancer genomics; memory B cell; precision medicine.

B-cell receptor activation, occurring within lymph nodes, plays a key role in the pathogenesis of chronic lymphocytic leukemia and is linked to prognosis. As well as activation of downstream signaling, receptor ligation triggers internalization, transit to acidified endosomes and degradation of ligand-receptor complexes. Herein, we investigated the relationship between these two processes in normal and leukemic B cells. We found that leukemic B cells, particularly anergic cases lacking the capacity to initiate downstream signaling, internalize and accumulate ligand in acidified endosomes more efficiently than normal B cells. Furthermore, ligation of either surface CD79B, a B-cell receptor component required for downstream signaling, or surface Immunoglobulin M (IgM) by cognate agonistic antibody, showed that the two molecules internalize independently of each other in leukemic but not normal B cells. Since association with surface CD79B is required for surface retention of IgM, this suggests that uncoupling of B-cell receptor internalization from signaling may be due to the dissociation of these two molecules in leukemic cells. A comparison of lymph node with peripheral blood cells from chronic lymphocytic leukemia patients showed that, despite recent B-cell receptor activation, lymph node B cells expressed higher levels of surface IgM. This surprising finding suggests that the B-cell receptors of lymph node- and peripheral blood-derived leukemic cells might be functionally distinct. Finally, long-term therapy with the Bruton's tyrosine kinase inhibitors ibrutinib or acalabrutinib resulted in a switch to an anergic pattern of B-cell receptor function with reduced signaling capacity, surface IgM expression and more efficient internalization.