Autoantibodies to B Lymphocytes in a Patient with Hypoimmunoglobulinemia: CHARACTERIZATION AND PATHOGENIC ROLE

In a young woman with ulcerative colitis, hypoimmunoglobulinemia, and humoral immunodeficiency, lymphocyte counts vary between 600 and 1,000 per mm³ with 0.5-1.5% bone marrow-derived (B) cells and 98-99% thymus-derived (T) cells. Anti-lymphocyte antibodies were detected by immunofluorescence and by microlymphocytotoxicity with increased reactivity at +4°C. They belonged to the IgM class and were polyclonal. Studies performed with various normal lymphocyte subpopulations, several lymphoblastoid cell lines and lymphocytes from immunodeficiency patients showed that these antibodies reacted with B cells. The corresponding antigen(s) is distinct from membrane-bound immunoglobulins, is not an alloantigen, and is probably unrelated to the la-like molecules. Pokeweed mitogen stimulated B cells appear to lose this antigen. Cells from various lymphoproliferative disorders were tested. T-derived and “non T-non-B” leukemic cells did not react with the antibody. Malignant cells from B-derived lymphomas and prolymphocytic leukemias were reactive. The incidence of positivity of the leukemic cells among patients with common B chronic lymphocytic leukemia was surprisingly low (one-third of the patients).

The autoantibody nature of the anti-B-cell antibodies and their pathogenic role in the genesis of the patient's hypoimmunoglobulinemia was demonstrated by the effect of removal of antibodies by massive plasmaphereses which were followed by a dramatic and transitory increase of B-cell figures. Whereas most primary immunodeficiency syndromes appear to result from an arrest in the differentiation capabilities of immunologically competent cells, autoantibodies to circulating B lymphocytes may be incriminated in the pathogenesis of some cases of hypogammaglobulinemia.

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