The effect of IgG fraction obtained from systemic lupus erythematosus (SLE) patients' serum on human bone marrow granulocyte-macrophage progenitor cells (CFU-C) derived colony formation

6 cases of systemic lupus erytemtosus (SLE) patients associated leukopenia were studied to evaluate the effect of their IgG fraction and peripheral blood mononuclear cells (MNC) on growth of granulocyte-macrophage progenitor cells (CFU-C) from normal human bone marrow. IgG fraction markedly suppressed the growth of CFU-C in all cases, although their serum suppressed in 3/6 cases. In 3/4 cases, bosh IgG fraction and MNC suppressed the CFU-C growth. These results suggest that the suppression of granulopoiesis by IgG or MNC may by participating with the pathogenesis of the leukopenia seen in SLE patients.