C-reactive protein (CRP) is an acute phase serum protein that shares several functions with immunoglobulin (Ig)G including complement activation and binding to receptors on monocytes and neutrophils. The identity of the receptor for CRP has been the target of extensive research. We previously determined that CRP binds to the high affinity receptor for IgG, FcgammaRI (CD64). However, this interaction could not account for the majority of binding of CRP to neutrophils or monocytic cells. We now determine that CRP also interacts with FcgammaRIIa (CD32), the low affinity receptor for IgG on monocytes and neutrophils. COS-7 cells were transfected with a construct containing the human FcgammaRIIA cDNA. CRP binding and the presence of CD32 were detected by mAb and analyzed by two-color flow cytometry. Cells expressing CD32 bound CRP in a dose-dependent and saturable manner consistent with receptor binding. CRP bound to transfectants and K-562 cells with similar kinetics, and in both cases binding was completely inhibited by aggregated IgG. On monocytic cell lines, treatment with Bt(2)cAMP increased FcgammaRII expression and enhanced CRP binding. CRP also specifically precipitated FcgammaRI and FcgammaRII from the monocytic cell line, THP-1. It is suggested that the major receptor for CRP on phagocytic cells is FcgammaRII.

Glycan structures attached to the C(H)2 domain of the Fc region of immunoglobulin G (IgG) are essential for specific effector functions but their role in modulating clearance is less clear. Clearance is of obvious importance for therapeutic monoclonal antibodies (Mabs) as it directly impacts efficacy. Here, we study the impact of Fc glycan structure on the clearance of four therapeutic human IgGs (one IgGGGs were affinity purified from serum samples from human pharmacokinetic studies, and changes to the glycan profile over time were determined by peptide mapping employing high-resolution mass spectrometry. Relative levels of high-mannose 5 (M5) glycan decreased as a function of circulation time, whereas other glycans remained constant. These results demonstrate that therapeutic IgGs containing Fc high-mannose glycans are cleared more rapidly in humans than other glycan forms. The quantitative effect of this on pharmacokinetic area under the curve was calculated and shown to be relatively minor for three of the four molecules studied, but, depending on the dosing regimen and the relative level of the high-mannose glycan, this can also have significant impact. High-mannose content of therapeutic Mabs should be considered an important product quality attribute which may affect pharmacokinetic properties of therapeutic antibodies.

The clinical utility of a human epidermal growth factor receptor 2 (HER2)-targeting Affibody molecule for detection and characterization of HER2-positive lesions was investigated in patients with recurrent metastatic breast cancer.

METHODS

Three patients received (111)In- or (68)Ga-labeled DOTA(0)-Z(HER2:342-pep2) (ABY-002). gamma-Camera, SPECT, or PET/CT images were compared with earlier (18)F-FDG PET/CT results.

RESULTS

Administration of radiolabeled ABY-002 was well tolerated. Blood kinetics of radiolabeled ABY-002 showed a first half-life of 4-14 min, second half-life of 1-4 h, and third half-life of 12-18 h. Radiolabeled ABY-002 detected 9 of 11 (18)F-FDG-positive metastases as early as 2-3 h after injection.

CONCLUSIONS

Molecular imaging using (111)In- or (68)Ga-labeled ABY-002 has the potential to localize metastatic lesions in vivo, adds qualitative information not available today by conventional imaging techniques, and may allow the HER2 status to be determined for metastases not amenable to biopsy. To our knowledge, this is the first report on clinical imaging data obtained with a non-immunoglobulin-based scaffold protein.

Monoclonal antibody (MAb)-based capture enzyme-linked immunosorbent assays (ELISAs) for the detection of anti-arboviral immunoglobulin G (IgG ELISAs) were developed for a comprehensive array of medically important arboviruses from the Alphavirus, Flavivirus, and Bunyavirus genera. Tests were optimized and standardized so that maximum homology could be maintained among working parameters for the different viral agents, enabling a wide range of viruses to be easily tested for at one time. MAbs were screened for suitability as capture vehicles for antigens from the three genera. The final test configuration utilized group-reactive MAbs eastern equine encephalitis virus 1A4B-6, dengue 2 virus 4GGG was detected by using alkaline phosphatase-conjugated anti-human IgG (Fc portion). A dilution of 1:400 was chosen as the universal screening serum dilution, with endpoint titrations of serum samples testing positive eliminating occasional false-positive results. IgG ELISA results correlated with those of the standard plaque-reduction neutralization assays. As expected, some test cross-reactivity was encountered within the individual genera, and tests were interpreted within the context of these reactions. The tests were standardized for laboratory diagnosis of arboviral infections, with the intent that they be used in tandem with the corresponding IgM antibody-capture ELISAs.

BACKGROUND

Improvement of rheumatoid arthritis (RA) during pregnancy has been causatively associated with increased galactosylation of immunoglobulin G (IgG) N-glycans. Since previous studies were small, did not include the postpartum flare and did not study sialylation, these issues were addressed in the present study.

METHODS

Serum from 148 RA cases and 32 healthy controls was collected at several time points before, during and after pregnancy. Improvement during pregnancy and postpartum flare were determined according to the European League Against Rheumatism (EULAR) response criteria. Galactosylation and sialylation of Immunoglobulin G (IgG) and the presence of bisecting N-acetylglucosamine (GlcNAc) were analyzed by matrix-assisted laser desorption/ionization - time of flight - mass spectrometry (MALDI-TOF-MS).

RESULTS

IgGGGalactosylation decreased directly postpartum. IgG galactosylation of controls was at a higher level than cases (P < 0.001 at all time points) and a similar pattern was observed for sialylation. Moreover, there was a good association between galactosylation and sialylation. The increase in galactosylation was significantly more pronounced for cases with improvement than cases without improvement during pregnancy. The reverse was true for deteriorators and non-deteriorators postpartum. The presence of bisecting GlcNAc was not significantly influenced by pregnancy or postpartum for cases and controls.

CONCLUSIONS

This large cohort study demonstrates the association of changes in galactosylation with both pregnancy-induced improvement and postpartum flare in RA-patients, suggesting a role for changes in glycosylation in the pregnancy-induced improvement of RA.

BACKGROUND

Recently, we described the discovery of a novel group 2 coronavirus, coronavirus HKU1 (CoV-HKU1), from a patient with pneumonia. However, the clinical and molecular epidemiological features of CoV-HKU1-associated pneumonia are unknown.

METHODS

Prospectively collected (during a 12-month period) nasopharyngeal aspirates (NPAs) from patients with community-acquired pneumonia from 4 hospitals were subjected to reverse-transcription polymerase chain reaction, for detection of CoV-HKU1. The epidemiological, clinical, and laboratory characteristics of patients with CoV-HKU1-associated pneumonia were analyzed. The pol, spike (S), and nucleocapsid (N) genes were also sequenced.

RESULTS

NPAs from 10 (2.4%) of 418 patients with community-acquired pneumonia were found to be positive for CoV-HKU1. All 10 cases occurred in spring and winter. Nine of these patients were adults, and 4 had underlying diseases of the respiratory tract. In the 6 patients from whom serum samples were available, all had a 4-fold change in immunoglobulin (Ig) G titer and/or presence of IgM against CoV-HKU1. The 2 patients who died had significantly lower hemoglobin levels, monocyte counts, albumin levels, and oxygen saturation levels on admission and had more-extensive involvement visible on chest radiographs. Sequence analysis of the pol, S, and N genes revealed 2 genotypes of CoV-HKU1.

CONCLUSIONS

CoV-HKU1 accounts for 2.4% of community-acquired pneumonia, with 2 genotypes in the study population. Without performance of diagnostic tests, the illness was clinically indistinguishable from other community-acquired pneumonia illnesses.

Human resting B lymphocytes enter a state of sustained proliferation when incubated with both mouse fibroblastic L cells stably expressing Fc gamma RII/CDw32 and anti-CD40 antibodies. We have explored the effects of 11 recombinant human cytokines (CKs) on induced cell proliferation and immunoglobulin (Ig) production. Interleukin 4 (IL-4) was the only CK able to enhance anti-CD40-induced B cell multiplication as measured by enumeration of viable cells, and interferon gamma (IFN-gamma) further stimulated this induced proliferation. IL-4 enhanced the production of IgM and IgG by B cells and induced them to produce IgE. Combinations of IL-4 and IL-2 resulted in the production of large amounts of IgM and IgA. Interestingly, IFN-gamma did not inhibit the production of IgE by cells stimulated with anti-CD40 and IL-4. None of the tested CK combinations resulted in the production of large quantities of IgG. Therefore, this new culture system represents a unique model to study isotype regulation in highly purified human B lymphocytes, in addition to allowing the generation of long-term factor-dependent human B cell lines.

Immunoglobulin class switch involves a unique recombination event that takes place at the region 5' to each heavy chain constant region gene during B lymphocyte differentiation. Such regions that are responsible for the class-switch recombination are defined as S regions (Kataoka et al., Proc. Natl. Acad. Sci. USA 77, 919, 1980). We have cloned a rearranged gamma 2b gene from a mouse myeloma (MPC11) and compared its structure with the germ line counterparts. The rearranged gamma 2b gene contained the 5' flanking region of the gamma 3 gene (S gamma 3 region) which are linked to the 5' flanking region of the gamma 2b gene (S gamma 2b region). We have determined nucleotide sequences surrounding the recombination site of the rearranged and germ line gamma 2b genes, which include the S gamma 2b and S gamma 3 regions. Both gamma 2b and S gamma 3 regions comprise tandem repetition of conserved units of 49 bp. Similar 49 bp repeating units are also found in the previously determined sequence of the S gamma 1 region in which class-switch recombination took place in MC101 myeloma. The nucleotide sequences of the S gamma 1, S gamma 2b and S gamma 3 repeating units share significant homology with each other. The S mu region, partial nucleotide sequence of which was previously determined, contains abundant short sequences such as AGCT, TGGG and AGCTGGGG which are shared in common by repeating sequences in S gamma regions. These results suggest that the recombination responsible for class switch from mu to gamma or from a gamma to another gamma, may be facilitated directly or indirectly by homology of repeating sequences in S regions.

A spectrum of in vivo-expressed Staphylococcus aureus antigens was identified by probing bacteriophage expression libraries of S. aureus with serum samples from infected and uninfected individuals. Eleven recombinant antigenic proteins were produced, and specific antibody titers in a large collection of human serum samples were determined. Significantly increased concentrations of reactive immunoglobulin G (IgG) to 7 antigens were found in serum samples from ill individuals, compared with those in healthy individuals. Significantly higher concentrations of reactive IgG to 4 antigens, including iron-responsive surface determinant (Isd) A and IsdH, were found in serum samples from healthy individuals who were not nasal carriers of S. aureus, compared with those in healthy carriers. Vaccination of cotton rats with IsdA or IsdH protected against nasal carriage. Also, IsdA is involved in adherence of S. aureus to human desquamated nasal epithelial cells and is required for nasal colonization in the cotton rat model. Thus, vaccination with these antigens may prevent S. aureus carriage and reduce the prevalence of human disease.

OBJECTIVE

Multiple tests are available for determining Helicobacter pylori infection. Our aim was to compare the sensitivity, specificity, and negative and positive predictive value of the most widely available tests for diagnosis of H. pylori.

METHODS

A total of 268 patients (mean age, 53.7 +/- 15.8 years; 142 male and 126 female; 125 white and 143 nonwhite) was tested for H. pylori infection by [13C]urea breath test (UBT), measurement of serum immunoglobulin (Ig) G and IgA antibody levels, and antral biopsy specimens for CLO test, histology, and Warthin-Starry stain. No patient received specific treatment for H. pylori before testing. The infection status for each patient was established by a concordance of test results.

RESULTS

Warthin-Starry staining had the best sensitivity and specificity, although CLO test, UBT, and IgG levels were not statistically different in determining the correct diagnosis. The absence of chronic antral inflammation was the best method to exclude infection. Stratification of results by clinical characteristics showed that UBT and chronic inflammation were the best predictors of H. pylori status in patients older than 60 years of age. IgA was a better predictor in white patients.

CONCLUSIONS

The noninvasive UBT and IgG serology test are as accurate in predicting H. pylori status in untreated patients as the invasive tests of CLO and Warthin-Starry.

The respiratory syncytial virus (RSV) G glycoprotein promotes differentiation of type 2 CD4+ T lymphocytes and induces an eosinophilic response in lungs of RSV-infected mice. A unique feature of G is that a second initiation codon in the transmembrane region of the glycoprotein results in secretion of soluble protein from infected cells. Recombinant vaccinia viruses that express wild-type G (vvWT G), only secreted G (vvM48), or only membrane-anchored G (vvM48I) were used to define the influence of G priming on immunopathogenesis. Mice immunized with vvM48 had more severe illness following RSV challenge than did mice primed with vvWT G or vvM48I. Coadministration of purified G during priming with the construct expressing membrane-anchored G shifted immune responses following RSV challenge to a more Th2-like response. This was characterized by increased interleukin-5 in lung supernatants and an increase in G-specific immunoglobulin GG-containing vectors but were greatest in mice primed with regimens including secreted G. These data suggest the form of G protein available for initial antigen processing and presentation is an important factor in promoting Th2-like immune responses, including the induction of lung eosinophilia. The ability of RSV to secrete G protein may therefore represent a viral strategy for immunomodulation and be a key determinant of disease pathogenesis.

It has been proposed that the increase in prevalence and severity of atopic disorders inversely correlates with exposure to infectious diseases such as tuberculosis. We have investigated this issue by combining an intranasal Mycobacterium bovis-Bacillus Calmette-Guérin (BCG) infection with a murine model of allergen, (ovalbumin [OVA]) induced airway eosinophilia. BCG infection either 4 or 12 wk before allergen airway challenge resulted in a 90-95 and 60-70% reduction in eosinophilia within the lungs, respectively, compared to uninfected controls. The inhibition of airway eosinophilia correlated with a reduced level of IL-5 production by T cells from the lymph node draining the site of OVA challenge. Interestingly, BCG infection of the lung had no effect on IgG1 and IgE OVA-specific serum immunoglobulin or blood eosinophil levels. Furthermore, BCG-induced inhibition of airway eosinophilia was strongly reduced in interferon (IFN)-gamma receptor-deficient mice and could be partially reversed by intranasal IL-5 application. Intranasal BCG infections could also reduce the degree of lung eosinophilia and IL-5 produced by T cells after Nippostrongylus brasiliensis infection. Taken together, our data suggest that IFN-gamma produced during the T helper cell (Th)1 immune response against BCG suppresses the development of local inflammatory Th2 responses in the lung. Most importantly, this inhibition did not extend to the systemic immunoglobulin response against OVA. Our data support the view that mycobacterial infections have the potential to suppress the development of atopic disorders in humans.

MUC1 is a highly attractive immunotherapeutic target owing to increased expression, altered glycosylation, and loss of polarity in >80% of human cancers. To exploit this, we have constructed a panel of chimeric Ag receptors (CAR) that bind selectively to tumor-associated MUC1. Two parameters proved crucial in optimizing the CAR ectodomain. First, we observed that the binding of CAR-grafted T cells to anchored MUC1 is subject to steric hindrance, independent of glycosylation status. This was overcome by insertion of the flexible and elongated hinge found in immunoglobulins of the IgD isotype. Second, CAR function was highly dependent upon strong binding capacity across a broad range of tumor-associated MUC1 glycoforms. This was realized by using an Ab-derived single-chain variable fragment (scFv) cloned from the HMFG2 hybridoma. To optimize CAR signaling, tripartite endodomains were constructed. Ultimately, this iterative design process yielded a potent receptor termed HOX that contains a fused CD28/OX40/CD3zeta endodomain. HOX-expressing T cells proliferate vigorously upon repeated encounter with soluble or membrane-associated MUC1, mediate production of proinflammatory cytokines (IFN-gamma and IL-17), and elicit brisk killing of MUC1(+) tumor cells. To test function in vivo, a tumor xenograft model was derived using MDA-MB-435 cells engineered to coexpress MUC1 and luciferase. Mice bearing an established tumor were treated i.p. with a single dose of engineered T cells. Compared with control mice, this treatment resulted in a significant delay in tumor growth as measured by serial bioluminescence imaging. Together, these data demonstrate for the first time that the near-ubiquitous MUC1 tumor Ag can be targeted using CAR-grafted T cells.

We have recently generated human papillomavirus (HPV) 16/E6E7 immortalized epithelial cell lines from the human vagina, ectocervix, and endocervix to use in studies on the role of these cells in reproduction and immune defense. The cell lines maintain the differentiation characteristics of their tissues of origin: the endocervical cell line expresses characteristics of simple columnar epithelium, whereas the ectocervical and vaginal cell lines express characteristics of stratified squamous nonkeratinizing epithelia. As a first step in elucidating the role of these cells in immune defense, we have studied the expression of immunological mediators in nonstimulated and stimulated cultures. Without stimulation, all three lines consistently produced the cytokines macrophage colony-stimulating factor (M-CSF) and transforming growth factor beta1, the chemokine interleukin (IL)-8, prostaglandin E2, the secretory leukoproteinase inhibitor, and the polymeric immunoglobulin receptor. The endocervical cell line, but not the others, also produced the lymphopoietic cytokines IL-6, IL-7, and consistently detectable levels of the chemokine known as "regulated-upon-activation, normal T cell expressed and secreted" (RANTES). Stimulation with the exogenous cytokines interferon gamma and tumor necrosis factor alpha induced or significantly up-regulated expression of several of the cytokines and chemokines (i.e., IL-6, IL-8, RANTES, and M-CSF), as well as major histocompatibility complex (MHC) class II antigens, and membrane expression and shedding of the intercellular adhesion molecule-1 in all three cell lines. These data provide further evidence that epithelial cells in the lower human female genital tract participate in immunological functions, that their activity is up-regulated by proinflammatory/immune cytokines, and that epithelial cell immunological functions vary at different anatomical sites in the genital tract.

One of the predominant polymicrobial infections of humans is expressed clinically as periodontal disease. Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia have been strongly implicated as members of a pathogenic consortium in the etiology of adult periodontitis. In this study we hypothesized that P. gingivalis, T. denticola, and T. forsythia are synergistic in terms of virulence potential and induce chronic periodontal inflammation that leads to alveolar bone resorption in a polymicrobial infection in rats. Groups of rats were infected with either P. gingivalis, T. denticola, or T. forsythia in monomicrobial infections or with all three species in polymicrobial oral infections with or without Fusobacterium nucleatum. PCR analyses of oral microbial samples demonstrated that rats infected with one bacterium were orally colonized by each of the bacteria during the study interval, and increased serum immunoglobulin G (IgG) antibody levels substantiated the interaction of the host with the infecting bacteria. PCR analyses of the rats with polymicrobial infections demonstrated that most rats were infected with P. gingivalis, T. denticola, and T. forsythia as a consortium. Furthermore, all rats exhibited a significant increase in the level of IgG antibody to the polymicrobial consortium. Radiographic measurement of alveolar bone resorption showed that rats infected with the polymicrobial consortium with or without F. nucleatum exhibited significantly increased alveolar bone resorption compared to the resorption in uninfected control rats, as well as the resorption in rats infected with one of the microbes. These results documented that P. gingivalis, T. denticola, and T. forsythia not only exist as a consortium that is associated with chronic periodontitis but also exhibit synergistic virulence resulting in the immunoinflammatory bone resorption characteristic of periodontitis.

Microcapsules of alginate cross-linked with divalent ions are the most common system for cell immobilization. In this study, we wanted to characterize the effect of different alginates and cross-linking ions on important microcapsule properties. The dimensional stability and gel strength increased for high-G alginate gels when exchanging the traditional Ca2+ ions with Ba2+. The use of Ba2+ decreased the size of alginate beads and reduced the permeability to immunoglobulin G. Strontium gave gels with characteristics lying between calcium and barium. Interestingly, high-M alginate showed an opposite behavior in combination with barium and strontium as these beads were larger than beads of calcium-alginate and tended to swell more, also resulting in increased permeability. Binding studies revealed that different block structures in the alginate bind the ions to a different extent. More specifically, Ca2+ was found to bind to G- and MG-blocks, Ba2+ to G- and M-blocks, and Sr2+ to G-blocks solely.

OBJECTIVE

Oral vaccine efficacy is low in less-developed countries, perhaps due to intestinal dysbiosis. This study determined if stool microbiota composition predicted infant oral and parenteral vaccine responses.

METHODS

The stool microbiota of 48 Bangladeshi infants was characterized at 6, 11, and 15 weeks of age by amplification and sequencing of the 16S ribosomal RNA gene V4 region and by Bifidobacterium-specific, quantitative polymerase chain reaction. Responses to oral polio virus (OPV), bacille Calmette-Guérin (BCG), tetanus toxoid (TT), and hepatitis B virus vaccines were measured at 15 weeks by using vaccine-specific T-cell proliferation for all vaccines, the delayed-type hypersensitivity skin-test response for BCG, and immunoglobulin G responses using the antibody in lymphocyte supernatant method for OPV, TT, and hepatitis B virus. Thymic index (TI) was measured by ultrasound.

RESULTS

Actinobacteria (predominantly Bifidobacterium longum subspecies infantis) dominated the stool microbiota, with Proteobacteria and Bacteroidetes increasing by 15 weeks. Actinobacteria abundance was positively associated with T-cell responses to BCG, OPV, and TT; with the delayed-type hypersensitivity response; with immunoglobulin G responses; and with TI. B longum subspecies infantis correlated positively with TI and several vaccine responses. Bacterial diversity and abundance of Enterobacteriales, Pseudomonadales, and Clostridiales were associated with neutrophilia and lower vaccine responses.

CONCLUSIONS

Bifidobacterium predominance may enhance thymic development and responses to both oral and parenteral vaccines early in infancy, whereas deviation from this pattern, resulting in greater bacterial diversity, may cause systemic inflammation (neutrophilia) and lower vaccine responses. Vaccine responsiveness may be improved by promoting intestinal bifidobacteria and minimizing dysbiosis early in infancy.

Galectin-1 (GAL-1), a member of a family of conserved beta-galactoside-binding proteins, has been shown to induce in vitro apoptosis of activated T cells and immature thymocytes. We assessed the therapeutic effects and mechanisms of action of delivery of GAL-1 in a collagen-induced arthritis model. A single injection of syngeneic DBA/1 fibroblasts engineered to secrete GAL-1 at the day of disease onset was able to abrogate clinical and histopathological manifestations of arthritis. This effect was reproduced by daily administration of recombinant GAL-1. GAL-1 treatment resulted in reduction in anticollagen immunoglobulin (Ig)G levels. The cytokine profile in draining lymph node cells and the anticollagen IgG isotypes in mice sera at the end of the treatment clearly showed inhibition of the proinflammatory response and skewing towards a type 2-polarized immune reaction. Lymph node cells from mice engaged in the gene therapy protocol increased their susceptibility to antigen-induced apoptosis. Moreover, GAL-1-expressing fibroblasts and recombinant GAL-1 revealed a specific dose-dependent inhibitory effect in vitro in antigen-dependent interleukin 2 production to an A(q)-restricted, collagen type 2-specific T cell hybridoma clone. Thus, a correlation between the apoptotic properties of GAL-1 in vitro and its immunomodulatory properties in vivo supports its therapeutic potential in the treatment of T helper cell type 1-mediated autoimmune disorders.

OBJECTIVE

To evaluate the effect of a combination of immunoglobulins (IVIg), cyclophosphamide (CTX), and methylprednisolone (MP) on the clinical course of patients with paraneoplastic neurological syndrome (PNS) and antineuronal antibodies (Abs).

METHODS

Seventeen patients with paraneoplastic encephalomyelitis/sensory neuropathy (PEM/SN) with anti-Hu Abs (n = 10) or cerebellar degeneration (PCD) with anti-Yo Abs (n = 7) received one to nine cycles (mean 3.5) of a combination of IVIg (0.5 g/kg/day from days 1 to 5), CTX (600 mg/m2 at day 1) and MP (1g/day from day 1 to 3). The Rankin scale (RS) was used to evaluate the response. A positive response was considered as either improvement or stabilisation in patients who were still ambulatory (RS< or =3) at the onset of treatment, whereas only improvement, and not stabilisation, was considered a therapeutic benefit in bedridden patients (RS> or =4).

RESULTS

Tolerance was good and no patient experienced grade 3/4 toxicity (World Health Organisation). Sixteen patients were evaluable for response. Of the seven patients with RS> or =4, none improved. Of the nine patients with RS< or =3, none improved but three (two SN and one PCD) stabilised for 4, 35, and 16 months.

CONCLUSIONS

This study suggests that vigorous immunosuppressive treatment is not useful in severely disabled PNS patients with antineuronal Abs. In a minority of patients (mainly with SN) who are not severely disabled at the onset of treatment, a transient stabilisation is possible and deserves further evaluation.

Natural killer (NK) cells play a major role in cancer immunotherapies that involve tumor-antigen targeting by monoclonal antibodies (mAbs). NK cells express a variety of activating and inhibitory receptors that serve to regulate the function and activity of the cells. In the context of targeting cells, NK cells can be "specifically activated" through certain Fc receptors that are expressed on their cell surface. NK cells can express FcγRIIIA and/or FcγRIIC, which can bind to the Fc portion of immunoglobulins, transmitting activating signals within NK cells. Once activated through Fc receptors by antibodies bound to target cells, NK cells are able to lyse target cells without priming, and secrete cytokines like interferon gamma to recruit adaptive immune cells. This antibody-dependent cell-mediated cytotoxicity (ADCC) of tumor cells is utilized in the treatment of various cancers overexpressing unique antigens, such as neuroblastoma, breast cancer, B cell lymphoma, and others. NK cells also express a family of receptors called killer immunoglobulin-like receptors (KIRs), which regulate the function and response of NK cells toward target cells through their interaction with their cognate ligands that are expressed on tumor cells. Genetic polymorphisms in KIR and KIR-ligands, as well as FcγRs may influence NK cell responsiveness in conjunction with mAb immunotherapies. This review focuses on current therapeutic mAbs, different strategies to augment the anti-tumor efficacy of ADCC, and genotypic factors that may influence patient responses to antibody-dependent immunotherapies.

Generation of local and systemic immune responses by the oral administration of antigens is frequently inefficient, requiring large quantities of immunogens and yielding only modest antibody responses. In this study, we have demonstrated that oral administration of microgram amounts of Streptococcus mutans protein antigen I/II covalently coupled to the B subunit of cholera toxin elicits vigorous mucosal as well as extramucosal immunoglobulin A and G antistreptococcal antibody responses in mice. These responses were manifested by the presence of large numbers of antibody-secreting cells in salivary glands, mesenteric lymph nodes, and spleens and by the development of high levels of circulating antibodies. This novel immunization strategy may find broad application in the construction of oral vaccines for the control of infectious diseases caused by pathogens encountered at mucosal and extramucosal sites.

Events that lead to phagocytosis of complement (C3)- or IgG-coated particles after their interaction with specific cell surface receptors are poorly understood. Two mouse monoclonal antibodies (an IgM and an IgG2a) to a human granulocyte-monocyte surface membrane differentiation antigen (Mol) inhibited ingestion by granulocytes both of oil Red O particles opsonized with normal human serum or with IgG and of sheep erythrocytes sensitized with IgG. In addition, they specifically inhibited rosetting between phagocytes and sheep erythrocytes coated with C3bi, a fragment of the complement component C3, generated by cleaving C3b with C3b inactivator and beta IH protein. These monoclonal anti-Mol antibodies did not inhibit IgG Fc, C3b or C3d receptor-mediated binding of erythrocytes coated with the respective proteins. The Fab fragment of the IgG2a monoclonal antibody inhibited noncytotoxic enzyme release from granulocytes when these cells were stimulated with zymosan coated with C3bi. Electrophoretic transfer of polymorphonuclear leukocyte detergent lysates to nitrocellulose, followed by immunofixation with monoclonal antibody, showed that these antibodies were directed to a 155,000-mol wt glycoprotein. This surface membrane structure appears to be involved in Fc and C3 receptor-dependent phagocytosis and closely associated with the C3bi receptor.

Cell-mediated immunity plays an essential role in the control of infection with the human cytomegalovirus (HCMV). However, only a few CD8(+)-T-cell epitopes are known, with the majority being contained in the pp65 phosphoprotein, which is believed to dominate the CD8(+)-T-cell response to HCMV. Here, we have readdressed the issue of CD8(+) T cells specific for the 72-kDa major immediate-early protein (IE-1), which is nonstructural but is found very early and throughout the replicative cycle. Using a novel flow-cytometric assay, we were able to identify CD8(+)-T-cell epitopes (by IE-1 peptide-specific induction of cytokine synthesis) and simultaneously measure the frequency of cells directed against them. For this purpose, 81 pentadecamer peptides covering the complete 491-amino-acid sequence of IE-1 were tested on peripheral blood mononuclear cells of anti-HCMV immunoglobulin G-seropositive donors. At least 10 new epitopes were identified, and the fine specificity and presenting HLA molecule of the first of them was determined. The frequencies of CD8(+) T cells directed against IE-1 were similar to those directed against pp65 in donors tested with known pp65-derived peptides. Importantly, additional testing of a corresponding set of peptides covering the complete sequence of pp65 on 10 of these donors identified individuals whose CD8(+) T cells recognized IE-1 but not pp65 and vice versa, clearly illustrating that either protein may be a major target. In summary, our results suggest that IE-1 is far more important as a CD8(+)-T-cell target than current opinion suggests.