Studies on anti-granulocyte and anti-platelet antibodies in patients with systemic sclerosis. Chemotaxis, phagocytosis and opsonized effect of PSS sera on normal granulocytes.

Autoantibodies may play a part in the pathogenesis of progressive systemic sclerosis (PSS). Anti-granulocyte antibodies have already been demonstrated in the sera of patients with PSS. In our study, anti-granulocyte antibodies were investigated by ELISA (enzyme linked immunosorbent assay) and cytotoxic tests. These antibodies were found in 18.4% of 38 patients. All the positive sera showed cold- and/or warm-reacting granulocytotoxic activity. No connection with granulocytopenia was found. The effect of patients' sera on normal granulocyte functions was also studied. Chemotaxis and binding of EA cells were inhibited independently of the presence of anti-granulocyte antibodies. Yeast phagocytosis and opsonized yeast phagocytosis were definitely reduced by sera containing anti-granulocyte antibodies. Anti-platelet autoantibodies were detected in 23.9% of the patients' sera, but no thrombocytopenia was found.