C1 and human platelets. Decrease in chronic lymphocyte leukemia. Effect of lymphocytes.

Studies of platelet C1 have been performed in 11 patients with chronic lymphocytic leukemia (CLL). The platelet C1 level evaluated by the hemolytic method was very low and the platelet aggregation induced by aggregated IgG or anti C1q antisera was significantly reduced. "In vitro", the lymphocytes from CLL were capable of inhibiting platelet C1 and platelet aggregation induced by aggregated IgG and anti C1q to a greater extent than normal lymphocytes. These results lead the authors to discuss the role of platelet C1 in the interaction platelet/immunoglobulins and the nature of the inhibition.