TWO DIFFERENT COMPLEMENT RECEPTORS ON HUMAN LYMPHOCYTES : ONE SPECIFIC FOR C3b AND ONE SPECIFIC FOR C3b INACTIVATOR-CLEAVED C3b

In the present study it was shown that normal peripheral lymphocytes have two different complement receptors: one for C3b (the immune adherence receptor) and one for C3b subsequent to its cleavage by C3b inactivator. The two receptors are not cross-reactive and were shown by tests with various antisera to be antigenically distinct. Both the immune adherence receptor and the receptor for C3b inactivator-cleaved C3b were found on normal peripheral lymphocytes and on cultured lymphoblastoid cells. In 15 out of 18 chronic lymphatic leukemia patients, the immune adherence receptor was either partially or completely missing from the peripheral lymphocytes, while the lymphocyte receptor for C3b inactivator-cleaved C3b was retained. Normal erythrocytes, on the other hand, were found to have only the immune adherence receptor. Granulocytes from normal peripheral blood appeared to have only a receptor for C3b and did not have a receptor for C3b inactivator-cleaved C3b.