BACKGROUND

To further increase the efficacy of malaria vaccine RTS,S/AS02A, we tested the RTS,S antigen formulated using the AS01B Adjuvant System (GlaxoSmithKline Biologicals).

METHODS

In a double-blind, randomized trial, 102 healthy volunteers were evenly allocated to receive RTS,S/AS01B or RTS,S/AS02A vaccine at months 0, 1, and 2 of the study, followed by malaria challenge. Protected vaccine recipients were rechallenged 5 months later.

RESULTS

RTS,S/AS01B and RTS,S/AS02A were well tolerated and were safe. The efficacy of RTS,S/AS01B and RTS,S/AS02A was 50% (95% confidence interval [CI], 32.9%-67.1%) and 32% (95% CI, 17.6%-47.6%), respectively. At the time of initial challenge, the RTS,S/AS01B group had greater circumsporozoite protein (CSP)-specific immune responses, including higher immunoglobulin (Ig) G titers, higher numbers of CSP-specific CD4(+) T cells expressing 2 activation markers (interleukin-2, interferon [IFN]-gamma, tumor necrosis factor-alpha, or CD40L), and more ex vivo IFN-gamma enzyme-linked immunospots (ELISPOTs) than did the RTS,S/AS02A group. Protected vaccine recipients had a higher CSP-specific IgG titer (geometric mean titer, 188 vs 73 mug/mL; P < .001), higher numbers of CSP-specific CD4(+) T cells per 10(6) CD4(+) T cells (median, 963 vs 308 CSP-specific CD4(+) T cells/10(6) CD4(+) T cells; P < .001), and higher numbers of ex vivo IFN-gamma ELISPOTs (mean, 212 vs 96 spots/million cells; P < .001). At rechallenge, 4 of 9 vaccine recipients in each group were still completely protected.

CONCLUSIONS

The RTS,S/AS01B malaria vaccine warrants comparative field trials with RTS,S/AS02A to determine the best formulation for the protection of children and infants. The association between complete protection and immune responses is a potential tool for further optimization of protection. Trial registration. ClinicalTrials.gov identifier NCT00075049.

Thymic stromal lymphopoietin (TSLP) is a cytokine that promotes CD4+ T cell homeostasis. We now demonstrate that TSLP is required to mount a normal CD4+ T cell-mediated inflammatory response. TSLP acts directly on naive, but not, memory CD4+ T cells, and promotes their proliferation in response to antigen. In addition, TSLP exerts an effect indirectly through DCs to promote Th2 differentiation of CD4+ T cells. Correspondingly, TSLP receptor (TSLPR) knockout (KO) mice exhibit strong Th1 responses, with high levels of interleukin (IL)-12, interferon-gamma, and immunoglobulin (Ig) G2a, but low production of IL-4, -5, -10, -13, and IgE; moreover, CD4+ T cells from these animals proliferate less well in response to antigen. Furthermore, TSLPR KO mice fail to develop an inflammatory lung response to inhaled antigen unless supplemented with wild-type CD4+ T cells. This underscores an important role for this cytokine in the development of inflammatory and/or allergic responses in vivo.

In the polymerase chain reaction (PCR), two specific oligonucleotide primers are used to amplify the sequences between them. However, this technique is not suitable for amplifying genes that encode molecules where the 5' portion of the sequences of interest is not known, such as the T cell receptor (TCR) or immunoglobulins. Because of this limitation, a novel technique, anchored polymerase chain reaction (A-PCR), was devised that requires sequence specificity only on the 3' end of the target fragment. It was used to analyze TCR delta chain mRNA's from human peripheral blood gamma delta T cells. Most of these cells had a V delta gene segment not previously described (V delta 3), and the delta chain junctional sequences formed a discrete subpopulation compared with those previously reported.

BACKGROUND

Infection with Helicobacter pylori is a major risk factor for the development of atrophic gastritis and gastric cancer. H. pylori strains can differ with respect to the presence of cagA (cytotoxin-associated gene A), a gene encoding a high-molecular-weight immunodominant antigen. H. pylori strains possessing cagA have been associated with enhanced induction of acute gastric inflammation.

OBJECTIVE

We investigated the relationship between cagA status and the development of atrophic gastritis in a cohort of subjects infected with H. pylori.

METHODS

Gastrointestinal endoscopy with biopsy sampling was used to study the natural history of gastritis in 58 subjects infected with H. pylori. Biopsy specimens were obtained before and after a mean follow-up period of 11.5 years (range, 10-13 years). The cagA status of each individual was determined at the follow-up visit with the use of an enzyme-linked immunosorbent assay designed to detect the presence of serum immunoglobulin G directed against the CagA protein. Two-sided Fisher's exact tests, McNemar's tests, Student's t tests, and Wilcoxon sum rank tests were used to analyze the data.

RESULTS

Twenty-four (41%) of the 58 evaluated subjects had serum antibodies against CagA (i.e., they were cagA positive), and 34 subjects were cagA negative. At the initial visit, moderate to severe atrophic gastritis was observed in eight (33%) of the cagA-positive subjects and in six (18%) of the cagA-negative subjects. At that time, positive cagA status and gastric atrophy were not significantly related (P = .22; Fisher's exact test; odds ratio [OR] 2.33; 95% confidence interval [CI] = 0.58-9.65). During follow-up, 16 (36%) of the 44 initially atrophy-negative subjects developed atrophic gastritis (eight [50%] of 16 cagA-positive subjects versus eight [29%] of 28 cagA-negative subjects; P = .20, Fisher's exact test; relative risk [RR] = 1.75; 95% CI = 0.82-3.76). In six of these 16 subjects (five cagA positive versus one cagA negative), atrophic gastritis was accompanied by the development of intestinal metaplasia (i.e., a change in the type of specialized cells present) (P = .02; Fisher's exact test; RR = 9.06; 95% CI = 1.16-71.0). One of the initially atrophy-negative, cagA-positive subjects developed early gastric cancer. Four (29%) of the 14 subjects initially diagnosed with atrophic gastritis showed regression of atrophy during follow-up (one cagA positive and three cagA negative). Therefore, at the end of follow-up, 15 (62%) of the 24 cagA-positive subjects had atrophic gastritis compared with 11 (32%) of the 34 cagA-negative subjects (P = .02; Fisher's exact test; OR = 3.48; 95% CI = 1.02-12.18).

CONCLUSIONS

Infection with cagA-positive H. pylori strains is associated with an increased risk for the eventual development of atrophic gastritis and intestinal metaplasia.

BACKGROUND

X-linked severe combined immunodeficiency (SCID-X1) is caused by mutations in the common cytokine-receptor gamma chain (gamma(c)), resulting in disruption of development of T lymphocytes and natural-killer cells. B-lymphocyte function is also intrinsically compromised. Allogeneic bone-marrow transplantation is successful if HLA-matched family donors are available, but HLA-mismatched procedures are associated with substantial morbidity and mortality. We investigated the application of somatic gene therapy by use of a gibbon-ape-leukaemia-virus pseudotyped gammaretroviral vector.

METHODS

Four children with SCID-X1 were enrolled. Autologous CD34-positive haemopoietic bone-marrow stem cells were transduced ex vivo and returned to the patients without preceding cytoreductive chemotherapy. The patients were monitored for integration and expression of the gamma(c) vector and for functional immunological recovery.

RESULTS

All patients have shown substantial improvements in clinical and immunological features, and prophylactic medication could be withdrawn in two. No serious adverse events have been recorded. T cells responded normally to mitogenic and antigenic stimuli, and the T-cell-receptor (TCR) repertoire was highly diverse. Where assessable, humoral immunity, in terms of antibody production, was also restored and associated with increasing rates of somatic mutation in immunoglobulin genes.

CONCLUSIONS

Gene therapy for SCID-X1 is a highly effective strategy for restoration of functional cellular and humoral immunity.

Since the first crystal structure of an immunoglobulin revealed a modular architecture, the characteristic beta-sheet fold of the immunoglobulin domain has been found in many other proteins of diverse biological function. Here, a systematic comparison of 23 Ig domain structures with less than 25% pairwise residue identity was performed using automatic structural alignment and analysis of beta-sheet and loop topology. Sequence consensus patterns were identified for nine distinct families with at most marginal similarity to each other. The analysis reveals a common structural core of only four beta-strands (b, c, e and f), embedded in an antiparallel curled beta-sheet sandwich with a total of three to five additional strands (a, c', c'', d, g) and a characteristic intersheet angle. The variation in the position of the edge strands (a, c', c'', d and g) relative to the common core defines four different topological subtypes that correlate with the length of the intervening sequence between strands c and e, the most variable region in sequence. The switch of strand c' from one sheet to the other in seven-stranded domains appears to result from short c-e segments, rather than being a major structural discriminator. The high degree of structural flexibility outside the common core and the extreme variability of side-chain packing inside the core do not support a protein folding pathway common to all members of the structural class. Mutation rates of immunoglobulin-like domains in different proteins vary considerably. Disulfide bridges, thought to contribute to structural stability, are not necessarily invariant in number and location within a subclass.

Titin, a 1-microm-long protein found in striated muscle myofibrils, possesses unique elastic and extensibility properties in its I-band region, which is largely composed of a PEVK region (70% proline, glutamic acid, valine, and lysine residue) and seven-strand beta-sandwich immunoglobulin-like (Ig) domains. The behavior of titin as a multistage entropic spring has been shown in atomic force microscope and optical tweezer experiments to partially depend on the reversible unfolding of individual Ig domains. We performed steered molecular dynamics simulations to stretch single titin Ig domains in solution with pulling speeds of 0.5 and 1.0 A/ps. Resulting force-extension profiles exhibit a single dominant peak for each Ig domain unfolding, consistent with the experimentally observed sequential, as opposed to concerted, unfolding of Ig domains under external stretching forces. This force peak can be attributed to an initial burst of backbone hydrogen bonds, which takes place between antiparallel beta-strands A and B and between parallel beta-strands A' and G. Additional features of the simulations, including the position of the force peak and relative unfolding resistance of different Ig domains, can be related to experimental observations.

The hinge region on the Fc fragment of human immunoglobulin G interacts with at least four different natural protein scaffolds that bind at a common site between the C(H2) and C(H3) domains. This "consensus" site was also dominant for binding of random peptides selected in vitro for high affinity (dissociation constant, about 25 nanomolar) by bacteriophage display. Thus, this site appears to be preferred owing to its intrinsic physiochemical properties, and not for biological function alone. A 2.7 angstrom crystal structure of a selected 13-amino acid peptide in complex with Fc demonstrated that the peptide adopts a compact structure radically different from that of the other Fc binding proteins. Nevertheless, the specific Fc binding interactions of the peptide strongly mimic those of the other proteins. Juxtaposition of the available Fc-complex crystal structures showed that the convergent binding surface is highly accessible, adaptive, and hydrophobic and contains relatively few sites for polar interactions. These are all properties that may promote cross-reactive binding, which is common to protein-protein interactions and especially hormone-receptor complexes.

Studies were performed to characterize the effector cells responsible for natural cytotoxicity of mouse lymphoid cells against a variety of syngeneic and allogeneic tumor lines. Since spleen cells from normal nude mice were found to be highly cytotoxic, they were used for most of these experiments. Only a small proportion of the reactivity was affected by treatment with anti-theta serum plus complement. Macrophages dis not appear to be responsible for the reactivity, since treatment with carbonyl iron/magnet or carrageenan did not affect the levels of cytotoxicity. The effector cells were non-adherent, since passage over nylon columns resulted in a considerable increase in activity. The active cells did not have receptors for immunoglobulin or complement, since removal of cells with these receptors by columns or monolayers containing sheep erythrocyte-antibody (EA) complexes or EA-complement complexes did not remove activity. Antibody-dependent cell-mediated cytotoxicity appeared to be ruled out as the mechanism for natural cytotoxicity, since aggregated gamma globulin and a potent anti-immunoglobulin reagent did not inhibit reactivity, and since no role for humoral factors could be demonstrated. The natural effector cell was found to be quite labile at 37 degrees C, losing much of its activity after 4 h. Since no surface markers could be detected on the effector cells, and the mechanism for cytotoxicity appeared distince from others previously described, it is proposed that the natural cytotoxicity against mouse tumor cells is mediated by a unique subpopulation of lymphoid cells, which are tentatively designated N-cells.

Staphylococcus aureus pneumonia causes significant mortality in hospitalized or healthy individuals, and recent increases in morbidity are attributed to the rapid spread of methicillin-resistant S. aureus (MRSA) strains, which are often not susceptible to antibiotic therapy. Alpha-hemolysin (Hla), a secreted pore-forming toxin, is an essential virulence factor of MRSA in a mouse model of S. aureus pneumonia. We show that the level of Hla expression by independent S. aureus strains directly correlates with their virulence. Active immunization with a mutant form of Hla (Hla(H35L)), which cannot form pores, generates antigen-specific immunoglobulin G responses and affords protection against staphylococcal pneumonia. Moreover, transfer of Hla-specific antibodies protects naive animals against S. aureus challenge and prevents the injury of human lung epithelial cells during infection. Thus, Hla vaccination or immunotherapy may prevent S. aureus pneumonia in humans.

Using a series of phenotypic markers that include immunoglobulin (Ig)D, IgM, IgG, CD23, CD44, Bcl-2, CD38, CD10, CD77, and Ki67, human tonsillar B cells were separated into five fractions representing different stages of B cell differentiation that included sIgD+ (Bm1 and Bm2), germinal center (Bm3 and Bm4), and memory (Bm5) B cells. To establish whether the initiation of somatic mutation correlated with this phenotypic characterization, we performed polymerase chain reaction and subsequent sequence analysis of the Ig heavy chain variable region genes from each of the B cell subsets. We studied the genes from the smallest VH families (VH4, VH5, and VH6) in order to facilitate the mutational analysis. In agreement with previous reports, we found that the somatic mutation machinery is activated only after B cells reach the germinal center and become centroblasts (Bm3). Whereas 47 independently rearranged IgM transcripts from the Bm1 and Bm2 subsets were nearly germline encoded, 57 Bm3-, and Bm4-, and Bm5-derived IgM transcripts had accumulated an average of 5.7 point mutations within the VH gene segment. gamma transcripts corresponding to the same VH gene families were isolated from subsets Bm3, Bm4, and Bm5, and had accumulated an average of 9.5 somatic mutations. We conclude that the molecular events underlying the process of somatic mutation takes place during the transition from IgD+, CD23+ B cells (Bm2) to the IgD-, CD23-, germinal center centroblast (Bm3). Furthermore, the analysis of Ig variable region transcripts from the different subpopulations confirms that the pathway of B cell differentiation from virgin B cell throughout the germinal center up to the memory compartment can be traced with phenotypic markers. The availability of these subpopulations should permit the identification of the functional molecules relevant to each stage of B cell differentiation.

Functional heavy-chain gamma-immunoglobulins lacking light chains occur naturally in Camelidae. We now show the feasibility of immunising a dromedary, cloning the repertoire of the variable domains of its heavy-chain antibodies and panning, leading to the successful identification of minimum sized antigen binders. The recombinant binders are expressed well in E. coli, extremely stable, highly soluble, and react specifically and with high affinity to the antigens. This approach can be viewed as a general route to obtain small binders with favourable characteristics and valuable perspectives as modular building blocks to manufacture multispecific or multifunctional chimaeric proteins.

Neuromyelitis optica is an inflammatory demyelinating disease of the central nervous system associated with autoantibodies against the glial water channel protein aquaporin-4. It has recently been reported that immunoglobulin from neuromyelitis optica patients injected peripherally does not cause lesions in naive rats, but only when pre-existing central nervous system inflammation is present. Here, we investigated whether immunoglobulin G from aquaporin-4-autoantibody-positive neuromyelitis optica patients has the potential to damage the central nervous system either alone or in the presence of human complement. Immunoglobulin G from neuromyelitis optica patients did not activate mouse complement and was not pathogenic when injected into mouse brain. However, co-injection of immunoglobulin G from neuromyelitis optica patients with human complement produced neuromyelitis optica-like lesions in mice. Within 12 h of co-injecting immunoglobulin G from neuromyelitis optica patients and human complement, there was a striking loss of aquaporin-4 expression, glial cell oedema, myelin breakdown and axonal injury, but little intra-parenchymal inflammation. At 7 days, there was extensive inflammatory cell infiltration, perivascular deposition of activated complement components, extensive demyelination, loss of aquaporin-4 expression, loss of reactive astrocytes and neuronal cell death. In behavioural studies, mice injected with immunoglobulin G from neuromyelitis optica patients and human complement into the right hemisphere preferentially turned to the right at 7 days. No brain inflammation, demyelination or right-turning behaviour was seen in wild-type mice that received immunoglobulin G from non-neuromyelitis optica patients with human complement, or in aquaporin-4-null mice that received immunoglobulin G from neuromyelitis optica patients with human complement. We conclude that co-injection of immunoglobulin G from neuromyelitis optica patients with human complement reproduces the key histological features of neuromyelitis optica and that aquaporin-4 is necessary and sufficient for immunoglobulin G from neuromyelitis optica patients to exert its effect. In our mouse model, immunoglobulin G from neuromyelitis optica patients does not require pre-existing central nervous system inflammation to produce lesions.

Anti-CD20 antibody immunotherapy effectively treats non-Hodgkin's lymphoma and autoimmune disease. However, the cellular and molecular pathways for B cell depletion remain undefined because human mechanistic studies are limited. Proposed mechanisms include antibody-, effector cell-, and complement-dependent cytotoxicity, the disruption of CD20 signaling pathways, and the induction of apoptosis. To identify the mechanisms for B cell depletion in vivo, a new mouse model for anti-CD20 immunotherapy was developed using a panel of twelve mouse anti-mouse CD20 monoclonal antibodies representing all four immunoglobulin G isotypes. Anti-CD20 antibodies rapidly depleted the vast majority of circulating and tissue B cells in an isotype-restricted manner that was completely dependent on effector cell Fc receptor expression. B cell depletion used both FcgammaRI- and FcgammaRIII-dependent pathways, whereas B cells were not eliminated in FcR common gamma chain-deficient mice. Monocytes were the dominant effector cells for B cell depletion, with no demonstrable role for T or natural killer cells. Although most anti-CD20 antibodies activated complement in vitro, B cell depletion was completely effective in mice with genetic deficiencies in C3, C4, or C1q complement components. That the innate monocyte network depletes B cells through FcgammaR-dependent pathways during anti-CD20 immunotherapy has important clinical implications for anti-CD20 and other antibody-based therapies.

Virtually all uropathogenic strains of Escherichia coli, the primary cause of cystitis, assemble adhesive surface organelles called type 1 pili that contain the FimH adhesin. Sera from animals vaccinated with candidate FimH vaccines inhibited uropathogenic E. coli from binding to human bladder cells in vitro. Immunization with FimH reduced in vivo colonization of the bladder mucosa by more than 99 percent in a murine cystitis model, and immunoglobulin G to FimH was detected in urinary samples from protected mice. Furthermore, passive systemic administration of immune sera to FimH also resulted in reduced bladder colonization by uropathogenic E. coli. This approach may represent a means of preventing recurrent and acute infections of the urogenital mucosa.

An interleukin-18 binding protein (IL-18BP) was purified from urine by chromatography on IL-18 beads, sequenced, cloned, and expressed in COS7 cells. IL-18BP abolished IL-18 induction of interferon-gamma (IFNgamma), IL-8, and activation of NF-kappaB in vitro. Administration of IL-18BP to mice abrogated circulating IFNgamma following LPS. Thus, IL-18BP functions as an inhibitor of the early Th1 cytokine response. IL-18BP is constitutively expressed in the spleen, belongs to the immunoglobulin superfamily, and has limited homology to the IL-1 type II receptor. Its gene was localized on human chromosome 11q13, and no exon coding for a transmembrane domain was found in an 8.3 kb genomic sequence. Several Poxviruses encode putative proteins highly homologous to IL-18BP, suggesting that viral products may attenuate IL-18 and interfere with the cytotoxic T cell response.

The protein responsible for malignant transformation by avian sarcoma viruses (ASVs) has been identified as a phosphoprotein of molecular weight 60,000 designated pp60src (refs 1--4). It has been suggested that this protein has a functional role in cellular transformation involving the phosphorylation of cellular proteins, for it was discovered that specific immunoprecipitates from ASV-transformed cells that contain pp60src catalysed the transfer of phosphate from [gamma-32P]ATP to the heavy chain of rabbit immunoglobulin. Additional studies involving the cell-free synthesis of the ASV src protein further demonstrated that the presence of the src polypeptide correlated with that presence of a phosphotransferase activity. Our studies, involving the biochemical purification of this protein, have demonstrated that the ASV-transforming gene product, pp60src, is itself a protein kinase. We have purified the pp60src protein approximately 5,000-fold using either conventional ion-exchange chromatography or immunoaffinity chromatography. The resultant partially purified preparations contain a cyclic AMP-independent protein kinase activity. We report here that the soluble phosphotransferase activity of partially purified pp60src results in the phosphorylation of exclusively tyrosine residues in a variety of proteins that serve as substrates.

Monocyte chemoattractant protein (MCP)-1 plays a critical role in innate immunity by directing the migration of monocytes into inflammatory sites. Recent data indicated a function for this chemokine in adaptive immunity as a regulator of T cell commitment to T helper cell type 2 (Th2) effector function. Studies in a Th1-dependent animal model, experimental autoimmune encephalomyelitis (EAE), showed that MCP-1 was highly expressed in the central nervous system (CNS) of affected rodents, and MCP-1 antibodies could block relapses of the disease. Mice deficient for the major MCP-1 receptor, CC chemokine receptor (CCR)2, did not develop EAE after active immunization but generated effector cells that could transfer the disease to naive wild-type recipients. We analyzed EAE in mice deficient for MCP-1 to define the relevant ligand for CCR2, which responds to murine MCP-1, MCP-2, MCP-3, and MCP-5. We found that C57BL/6 MCP-1-null mice were markedly resistant to EAE after active immunization, with drastically impaired recruitment of macrophages to the CNS, yet able to generate effector T cells that transferred severe disease to naive wild-type recipients. By contrast, adoptive transfer of primed T cells from wild-type mice into naive MCP-1-null recipients did not mediate clinical EAE. On the SJL background, disruption of the MCP-1 gene produced a milder EAE phenotype with diminished relapses that mimicked previous findings using anti-MCP-1 antibodies. There was no compensatory upregulation of MCP-2, MCP-3, or MCP-5 in MCP-1-null mice with EAE. These results indicated that MCP-1 is the major CCR2 ligand in mice with EAE, and provided an opportunity to define the role of MCP-1 in EAE. Compared with wild-type littermates, MCP-1-/- mice exhibited reduced expression of interferon gamma in draining lymph node and CNS and increased antigen-specific immunoglobulin G1 antibody production. Taken together, these data demonstrate that MCP-1 is crucial for Th1 immune responses in EAE induction and that macrophage recruitment to the inflamed CNS target organ is required for primed T cells to execute a Th1 effector program in EAE.

We have studied the distribution of myosin molecules in human cells using myosin-specific antibody coupled with fluorescent dyes. Rabbits were immunized with platelet myosin or myosin rod. They produced antisera which precipitated only myosin among all the components in crude platelet extracts. From these antisera we isolated immunoglobulin-G (IgG) and conjugated it with tetramethylrhodamine or fluorescein. We separated IgG with 2-5 fluorochromes per molecule from both under- and over-conjugated IgG by ion exchange chromatography and used it to stain acetone-treated cells. The following controls established the specificity of the staining patterns: (a) staining with labeled preimmune IgG; (b) staining with labeled immune IgG adsorbed with purified myosin; (c) staining with labeled immune IgG mixed with either unlabeled preimmune or immune serum; and (d) staining with labeled antibody purified by affinity chromatography. In blood smears, only the cytoplasm of platelets and leukocytes stained. In spread Enson and HeLa cells, stress fibers stained strongly in closely spaced 0.5 mum spots. The cytoplasm stained uniformly in those cells presumed to be motile before acetone treatment. In dividing HeLa cells there was a high concentration of myosin-specific staining in the vicinity of the contractole ring and in the mitotic spindle, especially the region between the chromosomes and the poles. We detected no staining of erythrocytes, or nuclei of leukocytes and cultured cells, or the surface of platelets and cultured cells.

Nucleotide sequences of a large number of V-(D)-J junctions of T cell receptor (TCR) gamma and delta genes show that most fetal thymocytes express on their surface one of just two gamma delta TCRs known to be expressed by epidermal gamma delta T cells (s-IEL) or intraepithelial gamma delta T cells associated with female reproductive organs (r-IEL). In contrast, gamma delta TCRs expressed on adult thymocytes are highly diverse as a result of multiple combinations of gene segments as well as junctional deletions and insertions, indicating that developmental time-and cell lineage-dependent mechanisms exist that control the extent of gamma delta TCR diversity. In addition, this study revealed a new type of junctional insertion (P nucleotides), which led to a new model of V-(D)-J joining generally applicable to immunoglobulin and TCR genes.

Biological agents have dramatically improved treatment options for patients with severe psoriasis. Etanercept (tumor necrosis factor [TNF] receptor-immunoglobulin fusion protein) is an effective treatment for many psoriasis patients, and blockade of TNF is considered to be its primary action. However, in this clinical trial, we show that etanercept has early inhibitory effects on a newly appreciated type of T cells: T helper type 17 (Th17) cells. Etanercept reduced the inflammatory dendritic cell products that drive Th17 cell proliferation (interleukin [IL] 23), as well as Th17 cell products and downstream effector molecules (IL-17, IL-22, CC chemokine ligand 20, and beta-defensin 4). In contrast, Th1 cellular products and effector molecules (interferon gamma, lymphotoxin alpha, and myxovirus resistance 1) were reduced late in disease resolution. This study suggests a role for Th17 in addition to Th1 cells in the pathogenesis of psoriasis. Th17 cells may be particularly important in driving epidermal activation in psoriatic plaques, whereas Th1 cells must also be eliminated for final disease resolution.

Hypogammaglobulinemia is the hallmark of common variable immunodeficiency (CVID) syndrome, a heterogeneous disorder predisposing patients to recurrent bacterial infections. In this study, we investigated the peripheral B-cell compartment of 30 well-characterized CVID patients in comparison to 22 healthy controls. Flow cytometric analysis of peripheral blood lymphocytes revealed a reduction of class-switched CD27(+)IgM(-)IgD(-) memory B cells below 0.4% in 77% of our patients (group I), while this B-cell subpopulation exceeded 0.5% in all healthy donors and in 23% of CVID patients (group II). These results correlate well with the capacity of peripheral blood lymphocytes to produce immunoglobulins in vitro upon stimulation with Staphylococcus aureus Cowan I (SAC) plus interleukin-2 because the production of immunoglobulin G in vitro is entirely dependent on the presence of switched memory B cells. The subdivision of group I into patients with an increased proportion of CD21(-) peripheral B cells >> 20%; group Ia) and patients with normal percentages of CD21(-) B cells (< 20%; group Ib) revealed a significant clustering of patients with splenomegaly and autoimmune cytopenias in group Ia. Based on these observations, we propose a fast and reliable new classification for CVID patients by flow cytometric quantification of class-switched memory and immature B cells in the peripheral blood of patients. Our results point toward defects at various stages of B-cell differentiation in CVID subgroups and support the value of a B-cell-oriented classification principle. A consensus on this new classification system will hopefully provide a tool for rapidly defining homogeneous subgroups of CVID for functional studies and genetic linkage analysis.

The remarkable success story of the therapeutic application of pooled immunoglobulin G (IgG) preparations from thousands of donors, the so-called intravenous IgG (IVIG) therapy, to patients with a variety of hematological and immunological disorders began more than half a century ago. Since then, the use of this primary blood product has increased constantly, resulting in the serious danger of shortages in supply. Despite its widespread use and therapeutic success, the mechanisms of action, especially of the anti-inflammatory activity, are only beginning to be understood. In this review, we summarize the clinical use of IVIG for different diseases and discuss recent data on the molecular mechanisms that might explain how this potent drug mediates its activity in vivo.

Borrelia burgdorferi dissemination to selected target organs was examined on days 1, 2, 3, 4, 7, 10, 15, 21, and 30 after intradermal inoculation of 4-week-old C3H mice. Infection was determined by culture (blood, spleen, kidney, ear punch); polymerase chain reaction (PCR) for outer surface protein A (OSP A) DNA (ear punch); histology and spirochete histochemistry (spleen, kidney, skin, heart, joints); and OSP A DNA in situ hybridization (joints, heart). Blood or spleen of most mice were culture positive by day 3 and ear punch by day 10. Polymerase chain reaction performed on ear punches was also positive by day 10. Inflammation of joints and tendons began on days 4 through 7 and heart on days 7 through 10, which coincided with colonization of tissues with spirochetes. Spirochetes were multifocal in distribution, with a predilection for collagenous connective tissue of joints, heart, arteries, nerves, muscle, skin, and other tissues. Relative numbers of spirochetes peaked at 15 days, then decreased by 21 days. Gamma M immunoglobulin (IgM) antibody was detectable on immunoblots as early as day 4, with subsequent declining reactivity, and IgG antibody was detectable by day 7, with expanding reactivity to multiple antigens through day 30.