ACTIVATION OF ALTERNATIVE COMPLEMENT PATHWAY BY LYMPHOBLASTOID CELL LINES DERIVED FROM PATIENTS WITH BURKITTS-LYMPHOMA AND INFECTIOUS-MONONUCLEOSIS

Cultured human lymphoblastoid cell lines derived from patients with Burkitt''s lymphoma or infectious mononucleosis activated the alternative pathway of complement [C] fixation. This reaction does not require any conventional antibody directed against the cells. Although the reaction showed an absolute dependence on the presence of the 3rd C component proactivator, it was relatively independent of the presence of C3 proactivator convertase precursor or of properdin. To this extent, activation of the alternative pathway by lymphoblastoid cells resembles that produced by C3-nephritic factor. Rat and mouse complement were activated in a manner similar to human complement, but guinea pig complement was inactive. Chicken complement, unlike any of the mammalian complements tested, was able to bring about lysis of the lymphoblastoid cell lines by the alternative pathway.