EFFECTS OF HUMAN MONOCLONAL ANTICARDIOLIPIN ANTIBODIES ON PLATELET-FUNCTION AND ON TISSUE FACTOR EXPRESSION ON MONOCYTES

Objective. To investigate the effect of human monoclonal anticardiolip in antibodies (aCL) on platelet interaction with the subendothelium un der flow conditions and on tissue factor (TF) expression on normal mon ocytes. Methods. Three monoclonal IgM aCL (TM1B3, GR1D5, and EY2C9) an d 2 affinity-purified IgM aCL were studied, Immunoglobulins were added to normal blood and perfused through chambers containing denuded vasc ular segments. Platelet interactions were morphometrically evaluated b y determining the percentage of total surface covered by platelets (PC S) or by large aggregates of thrombi platelets (TP). Expression of TP on monocytes was measured after immunoglobulin incubation with normal mononuclear cells. Results. Significant increases in the total PCS and expression of TP mere observed using all aCL, Increased Bevels of TP were induced by all aCL except EY2C9 (obtained from a patient without thrombosis). Previous incubations of these aCL with subendothelial sur faces did not increase platelet interaction. Conclusion. The effects o f aCL on platelet function may help to explain the pathophysiology of thrombosis in the antiphospholipid syndrome.