Abstract
Earlier studies showed that the DNA-binding protein, Bright/ARID3a bound to a subset of human and mouse immunoglobulin heavy chain promoters where it enhanced expression. Indeed, mice with transgenic expression of ARID3a in all B lymphocytes have expanded MZ B cells and produce anti-nuclear antibodies (ANAs). Consistent with our findings in mice, we observed that human systemic lupus erythematosus (SLE) patients had expanded numbers of peripheral blood ARID3a+ B cells that were associated with increased disease activity (p = 0.0038). We hypothesized that ARID3a+ naïve B cells would eventually produce autoantibodies, explaining associations between ARID3a expression and disease activity in lupus. Unlike healthy controls, ARID3a was expressed in the naïve B cell population in SLE patients, and we hypothesized that these might represent expansions of autoreactive cells. Therefore, monoclonal antibodies were generated from single-sorted naïve B cells derived from patients with normal (ARID3aN) and high (ARID3aH) numbers of ARID3a+ B cells. We found that ARID3a expression did not correlate with autoantibody expression. Furthermore, measures of antigen specificities of autoreactive antibodies did not reveal skewing toward particular proteins. These data suggest that the association of increased disease activity in SLE with numbers of ARID3a+ B lymphocytes may be mediated by an antibody-independent mechanism.
Highlights
IntroductionWe found that transgenic mice constitutively over-expressing ARID3a in all B lymphocytes produced anti-nuclear antibodies by four weeks of age, and on multiple genetic backgrounds [1,2]
We found that transgenic mice constitutively over-expressing ARID3a in all B lymphocytes produced anti-nuclear antibodies by four weeks of age, and on multiple genetic backgrounds [1,2].These data linked ARID3a expression with autoimmunity and the generation of autoantibodies
Previous studies indicated that systemic lupus erythematosus (SLE) patients with numbers of ARID3a+ B cells more than two standard deviations above the mean numbers found in healthy controls (ARID3aH, high samples) had increased disease activity relative to patient samples with normal numbers of ARID3a+ B cells (ARID3aN, normal samples) [3]
Summary
We found that transgenic mice constitutively over-expressing ARID3a in all B lymphocytes produced anti-nuclear antibodies by four weeks of age, and on multiple genetic backgrounds [1,2]. These data linked ARID3a expression with autoimmunity and the generation of autoantibodies. We performed cross-sectional and longitudinal studies of systemic lupus erythematosus (SLE) patients to determine if ARID3a is over-expressed in human autoimmune disease [3]. Those studies revealed that 43% of SLE patients have expanded ARID3a+ B cells, and that total numbers of
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