Abstract
The detection of anti-platelet antibody by ADCC method was performed on ten patients with ITP, 19 patients with SLE, 7 patients with AML and 6 patients with the aplastic anemia. The anti-platelet antibody was positive in 100% of ITP patients, 58% of SLE patients, 14% of AML patients and 50% of aplastic anemia patients. The ADCC was inhibited by the addition of 3μg of aggregated IgG, suggesting the high sensitivity of the detection of anti-platelet antibody. The ADCC detected not only anti-platelet autoantibody but also anti-platelet isoantibody. K cells were not decreased in ITP patients, but the decrease of K cell functions was demonstrated in SLE patients. The decrease of K cell functions in SLE lymphocytes was restored by the thorough washing and the culture of SLE lymphocytes. The decrease of K cell functions of SLE lymphocytes is probably caused by the in vivo binding of immune complexes to Fc receptors of K cells. There have been many cases, which shows no decrease of platelet counts in spite of the presence of anti-platelet antibody, in SLE. This might be probably caused by the decrease of K cell functions due to binding of immune complexes to Fc receptors of K cells. The scanning electronmicroscopic examinations demonstrated many microvilli on K cells. The Fc receptors were not present on these microvilli. They were present deep on the cell membranes.
