Lymphocytopenia in lupus erythematosus: close in vivo association to autoantibodies targeting nuclear antigens

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Abstract
Background Leukopenia and lymphopenia are typical features of lupus erythematosus (LE) and correlate with elevated disease activity and higher grades of systemic involvement. Antilymphocyte antibodies are regarded as the most likely rationale for the decreased cell numbers; however, their relevance has not been confirmed so far. Objectives Previous investigations at our department have shown a significant correlation between diminished lymphocyte numbers and the presence of antinuclear antibodies (ANA). We wanted to achieve a better understanding of this phenomenon. Methods We performed a detailed analysis of autoantibodies and peripheral leucocyte subsets in 82 patients with different subtypes of LE. Leucocyte subsets were measured using flow cytometry (FACScanTM; Becton Dickinson, Franklin Lakes, NJ, U.S.A.); autoantibodies were detected by indirect immunofluorescence and by enzyme‐linked immunosorbent assay. Results A significant association (P < 0·05) between specific antibodies targeting nuclear antigens (SSA/Ro‐52, SSB/La, snRNPs) and lymphocytopenia was found. Conclusions We suppose that some of these autoantibodies might have an antilymphocyte effect. Apoptosis induction by specific antinuclear antibodies has already been described earlier, but to the best of our knowledge this is the first study presenting a strong indication of a possible interaction between these antibodies and lymphocyte subsets in vivo.