Serum levels of soluble CD21 in patients with systemic sclerosis.

Systemic sclerosis (SSc) is a systemic disorder that typically results in fibrosis of the skin and multiple internal organ systems. Although the precise mechanism is unknown, overproduction of extracellular matrix proteins, including collagens and fibronectins, and aberrant immune activation might be involved in the pathogenesis. The soluble cluster of differentiation 21 (sCD21) represents the extracellular portion of the CD21 glycoprotein that is released by shedding from the cell surfaces into plasma. sCD21 binds complement fragments and activates monocytes through binding to membrane CD23. The present study was undertaken to investigate the serum levels of sCD21 in patients with SSc. Serum sCD21 levels were reduced with age both in patients with SSc and normal controls. Serum sCD21 levels in patients with SSc were significantly decreased compared to those in control subjects. When we divided patients with SSc into limited cutaneous SSc (lcSSc) and diffuse cutaneous SSc (dcSSc), patients with lcSSc had lower levels of serum sCD21 than those with dcSSc. Moreover, the prevalence of pulmonary fibrosis in the patients with dcSSc inversely correlated with serum sCD21 levels. Our finding may support the notion that B-cell activation is involved in the mechanism for pulmonary fibrosis and skin sclerosis.

Clinical usefulness of anti-RNA polymerase III antibody measurement by enzyme-linked immunosorbent assay.

OBJECTIVE: To evaluate the clinical usefulness of measuring anti-RNA polymerase (RNAP) III antibody with a commercially available ELISA in Japanese patients with SSc. METHODS: This multicentre study involved 354 patients with SSc, 245 with non-SSc CTDs and 102 healthy controls. ELISAs were used to detect anti-RNAP III antibody, anti-topo I antibody and ACA. The presence of anti-RNAP III antibody in selected serum samples was confirmed by immunoprecipitation (IP) assay. RESULTS: By ELISA, anti-RNAP III antibody was detected in 38 (10.7%) patients with SSc, 3 (1.2%) with non-SSc CTD and no healthy controls. The clinical specificity for SSc was excellent (98.8%), although a small number of false positives occurred. The sensitivity of the anti-topo I and ACA ELISAs for SSc was 59.9%, which increased to 68.2% without a reduction in specificity when the anti-RNAP III measurement was added. Clinical features associated with positivity for the anti-RNAP III antibody include dcSSc, a high total skin score and a trend towards high prevalence of renal crisis, consistent with previous studies that used an IP assay. Furthermore, on clinical severity scales, SSc patients with anti-RNAP III antibody scored highest for skin and renal involvement among patients subgrouped by the presence of individual SSc-related antibodies. CONCLUSIONS: The measurement of anti-RNAP III antibody by ELISA is useful in routine clinical practice, because it helps diagnose SSc and identify a disease subset with severe skin and renal involvement.

Serum levels of IgE anti-BP180 and anti-BP230 autoantibodies in patients with bullous pemphigoid.

BACKGROUND: Bullous pemphigoid (BP) is a subepidermal blistering disease characterized by autoantibodies against the hemidesmosomal proteins, BP180 and BP230. NC16A, a non-collagenous stretch of the BP180 ectodomain is the primary target of pathogenic IgG antibodies. Whereas IgG anti-BP180 autoantibodies play a primary role in the pathogenesis, there is a growing number of data regarding the potential pathogenic roles of IgE class autoantibodies in BP. OBJECTIVES: To examine the levels of IgG and IgE autoantibodies against BP180 and BP230, and to investigate mutual association and clinical relevance. METHODS: Sera obtained from 67BP patients and 36 healthy donors were subjected to ELISA assays to measure serum IgG and IgE levels of anti-BP180 and anti-BP230 antibodies. RESULTS: IgG anti-BP180 antibodies were positive in 63 (94%) of 67BP patients. IgG anti-BP230, IgE anti-BP180, and IgE anti-BP230 antibodies were found in 48 (72%), 20 (30%) and 45 (67%), respectively. IgG anti-BP180 levels were correlated with the affected areas. IgG anti-BP230 antibodies tended to increase in proportion to elongation of disease duration. IgE anti-BP230 levels showed a strong association with local eosinophil accumulation, while the levels were reversely related with the affected areas in BP. CONCLUSIONS: IgE autoantibodies to BP180 and BP230 are detected at high frequencies in BP. IgE anti-BP230 antibodies may have a role in attracting eosinophils to the skin lesions.

Recent advances on pathogenesis and therapies in systemic sclerosis.

Systemic sclerosis (SSc) is a systemic autoimmune disease characterized by extensive fibrotic changes in various organs, including skin and lung. Although the etiology of SSc remains unknown, three major abnormalities, abnormal humoral immunity, microvasculature, and fibroblast dysfunctions are considered to play important roles. Significant progress has been made in understanding the pathogenesis on SSc, and has been also providing clues to the treatment for this disease. This review summarizes recent advances on the pathogenesis and new therapeutic strategy for SSc.

CD83 expression is a sensitive marker of activation required for B cell and CD4+ T cell longevity in vivo.

CD83 is a surface marker that differentiates immature and mature human dendritic cell populations. Thymic epithelial cell expression of CD83 is also necessary for efficient CD4+ T cell development in mice. The altered phenotypes of peripheral B and CD4+ T cells, and the reduction of peripheral CD4+ T cells in CD83-/- mice, suggest additional functions for CD83. To assess this, a panel of mAbs was generated to characterize mouse CD83 expression by peripheral leukocytes. As in humans, activation of conventional and plasmacytoid murine dendritic cell subsets led to rapid up-regulation of CD83 surface expression in mice. In primary and secondary lymphoid compartments, a subset of B cells expressed low-level CD83, while CD83 was not detected on resting T cells. However, CD83 was prominently up-regulated on the majority of spleen B and T cells within hours of activation in vitro. In vivo, a low dose of hen egg lysozyme (1 microg) induced significant CD83 but not CD69 expression by Ag-specific B cells within 4 h of Ag challenge. Although B cell development appeared normal in CD83-/- mice, B and CD4+ T cell expression of CD83 was required for lymphocyte longevity in adoptive transfer experiments. Thus, the restricted expression pattern of CD83, its rapid induction following B cell and T cell activation, and its requirement for B cell and CD4+ T cell longevity demonstrate that CD83 is a functionally significant and sensitive marker of early lymphocyte activation in vivo.

CD83 influences cell-surface MHC class II expression on B cells and other antigen-presenting cells.

CD83 is a member of the Ig superfamily expressed primarily by mature dendritic cells (DCs). In mice, CD83 expression by thymic stromal cells regulates CD4(+) T cell development, with CD83(-/-) mice demonstrating dramatic reductions in both thymus and peripheral CD4(+) T cells. In this study, CD83 expression was also found to affect MHC class II antigen expression within the thymus and periphery. CD83 deficiency reduced cell-surface class II antigen expression by 25-50% on splenic B cells and DCs, thymic epithelial cells and peritoneal macrophages. Reduced class II expression was a stable and intrinsic property that resulted from increased internalization of class II from the surface of CD83(-/-) B cells. Otherwise, class II antigen transcription, intracellular expression, heterodimer structure, antigen processing and antigen presentation were normal. Reduced class II antigen expression was not the primary cause of the CD83(-/-) phenotype since thymocyte and peripheral T cell development was normal in class II(+/-) mice. Comparable blocks in CD4(+) thymocyte development were also observed in CD83(-/-) and CD83(-/-)class II(+/-) littermates. TCR and CD69 expression patterns in CD83(-/-) mice further suggested that double-positive thymocytes proceed through the class II-dependent stages of positive selection in the absence of CD83. These studies further emphasize a role for CD83 in lymphocyte development and immune regulation and reveal an unexpected role for CD83 expression in influencing cell-surface MHC class II turnover.

CD19 expression in B cells is important for suppression of contact hypersensitivity.

Contact hypersensitivity (CHS) is a cutaneous immune reaction mediated mainly by antigen-specific effector T cells and is regarded as a model for Th1/Tc1-mediated inflammation. However, recent reports have suggested pivotal roles of B cells in CHS. CD19 serves as a positive B-cell response regulator that defines signaling thresholds critical for B-cell responses. In the current study, we assessed the role of the B-cell-specific surface molecule CD19 on the development of CHS by examining CD19-deficient mice. Although CD19-deficient mice are hyposensitive to a variety of transmembrane signals, CD19 loss resulted in increased and prolonged reaction of CHS, suggesting an inhibitory role of CD19 expression in CHS. Sensitized lymph nodes and elicited ear lesions from CD19-deficient mice exhibited Th1/Tc1-shifted cytokine profile with increased interferon-gamma expression and decreased interleukin-10 expression. Adoptive transfer experiments revealed that CD19 expression in recipient mice was required for optimal suppression of CHS response, indicating its role in the elicitation phase. Furthermore, spleen B cells, especially marginal zone B cells, from wild-type mice were able to normalize exaggerated CHS reactions in CD19-deficient mice. Thus, CD19 expression in B cells is critical for termination of CHS responses, possibly through the function of regulatory B cells.

Bullous pemphigoid positive for anti-BP180 and anti-laminin 5 antibodies in a patient with graft-vs-host disease.

We report the case of a 55-year-old female with bullous pemphigoid (BP) who was positive for anti-BP180 and anti-laminin 5 antibodies after development of graft-vs-host disease (GVHD) caused by a bone marrow transplant. She had tense blisters on her trunk and extremities. Histologic examination showed a subepidermal blister and marked lymphocytic infiltration, especially eosinophils. Direct immunofluorescence revealed a linear deposition of IgG on the base membrane zone. Indirect immunofluorescence on 1M NaCl split skin revealed a linear IgG deposition to both sides of the epidermal and the dermal layers. Immunoblot assays using human epidermal extracts and BP180 NC16a domain recombinant protein confirmed the presence of IgG antibodies against BP180 and recombinant BP180 NC16a domain protein. Furthermore, immunoblotting using laminin 5 purified from human keratinocyte extract as the substrate demonstrated reactivity against the gamma2 and beta3 subunits but not the alpha3 subunit of laminin 5. We diagnosed BP and treated her with prednisolone (40 mg/day). Both skin and oral lesions resolved without leaving scars on the bulla. Immune disturbance as well as destruction of basal epidermal cells and base membrane by GVHD may result in the induction of autoimmune blistering diseases with unusual clinical and laboratory manifestations.

Serum anti-Fcgamma receptor autoantibodies in patients with alopecia areata.

Although anti-Fcgamma receptor antibodies (Abs) are detected in various autoimmune diseases, there have been no studies about the anti-Fcgamma receptor Abs in alopecia areata (AA). To detect the anti-Fcgamma receptor Abs in patients with AA and their clinical correlations, Serum samples from 72 patients with AA and 23 normal controls were examined by enzyme-linked immunosorbent assay assessing anti-Fcgamma receptor Ab levels. Anti-Fcgamma receptor I Abs were significantly frequently detected in patients with AA compared with normal controls. Furthermore, the detection of anti-Fcgamma receptor I Abs significantly inversely correlated with the disease duration. These results suggest that anti-Fcgamma receptor I Ab and Fcgamma receptor I play an important role in the regulation of AA, are useful for a marker of the disease prognosis and are worth intense research for the reasonable and specific therapy of AA.

Anti-p53 antibodies in patients with dermatomyositis/polymyositis.

Dermatomyositis/polymyositis (DM/PM), which is often accompanied by various immunological abnormalities, was reported to be associated with an increased incidence of malignancies. In this study, we analyzed serum levels of anti-p53 antibody (anti-p53 Ab) in DM/PM patients and in normal controls. Serum levels of anti-p53 Abs were significantly higher in DM/PM patients than those in healthy controls. However, there was no significant difference between serum levels in patients with malignancies and those in patients without malignancies. Anti-p53 Abs were positive in 13% (4 out of 31) of the DM/PM patients. Of these four patients, only one had an internal malignancy. Immunoglobulin G levels were significantly higher in patients positive for anti-p53 Ab than those who were not. These results seemed to suggest that the presence of anti-p53 Abs in DM/PM patients is due to immunological abnormalities in this disease.

Immunotherapy using unconjugated CD19 monoclonal antibodies in animal models for B lymphocyte malignancies and autoimmune disease.

Immunotherapy with unconjugated CD20 monoclonal antibodies has proven effective for treating non-Hodgkin's lymphoma and autoimmune disease. CD20 immunotherapy depletes mature B cells but does not effectively deplete pre-B or immature B cells, some B cell subpopulations, antibody-producing cells, or their malignant counterparts. Because CD19 is expressed earlier during B cell development, a therapeutic strategy for the treatment of early lymphoblastic leukemias/lymphomas was developed by using CD19-specific monoclonal antibodies in a transgenic mouse expressing human CD19. Pre-B cells and their malignant counterparts were depleted as well as antibody- and autoantibody-producing cells. These results demonstrate clinical utility for the treatment of diverse B cell malignancies, autoimmune disease, and humoral transplant rejection.

Anti-agalactosyl immunoglobulin G antibodies in localized scleroderma.

BACKGROUND: Anti-agalactosyl immunoglobulin G (IgG) antibodies (anti-AG IgG) have been reported to be detected and correlated with disease activity in some collagen diseases. METHOD: Forty-seven serum samples from patients with localized scleroderma were examined using an enzyme-linked immunosorbent assay. RESULTS: Anti-AG IgG were positive in 19% of patients with localized scleroderma. The frequency of anti-AG IgG in generalized morphea was much higher than that in linear scleroderma or that in morphea. There was a significant correlation between anti-AG IgG levels and the number of the sclerotic lesions and between anti-AG IgG levels and the number of involved areas. The levels of anti-AG IgG were significantly higher in patients with antinuclear antibody, antisingle-stranded DNA antibody or rheumatoid factor than in those without. CONCLUSION: Anti-AG IgG can be an indicator of the severity of localized scleroderma.

B Lymphocyte signaling established by the CD19/CD22 loop regulates autoimmunity in the tight-skin mouse.

Systemic sclerosis (SSc) is characterized by fibrosis and autoimmmunity. Peripheral blood B cells from SSc patients specifically overexpress CD19, a critical cell-surface signal transduction molecule in B cells. CD19 deficiency in B cells also attenuates skin fibrosis in the tight-skin (TSK/+) mouse, a genetic model for SSc. Herein we analyzed two transgenic mouse lines that overexpress CD19. Remarkably, 20% increase of CD19 expression in mice spontaneously induced SSc-specific anti-DNA topoisomerase I (topo I) antibody (Ab) production, which was further augmented by 200% overexpression. In TSK/+ mice overexpressing CD19, skin thickness did not increase, although anti-topo I Ab levels were significantly augmented, indicating that abnormal CD19 signaling influences autoimmunity in TSK/+ mice and also that anti-topo I Ab does not have a pathogenic role. The molecular mechanisms for abnormal CD19 signaling were further assessed. B-cell antigen receptor crosslinking induced exaggerated calcium responses and augmented activation of extracellular signal-regulated kinase in TSK/+ B cells. CD22 function was specifically impaired in TSK/+ B cells. Consistently, CD19, a major target of CD22-negative regulation, was hyperphosphorylated in TSK/+ B cells. These findings indicate that reduced inhibitory signal provided by CD22 results in abnormal activation of signaling pathways including CD19 in TSK/+ mice and also suggest that this disrupted B cell signaling contribute to specific autoantibody production.