RECEPTOR FOR SOLUBLE C3 AND C3b ON HUMAN LYMPHOBLASTOID (RAJI) CELLS PROPERTIES AND BIOLOGICAL SIGNIFICANCE

摘要: This study describes the presence of a receptor for fluid phase human C3 and C3b on Raji cell membranes. The binding was demonstrated indirectly by fluoresceinated anti-C3 serum directly using radioiodinated proteins. No other complement proteins or factors were needed to mediate receptor. possibility enzymatic cleavage before after its attachment membrane ruled out demonstration antigenically intact cells. Inhibition dissociation cell-EAC1423 rosettes indicated that both these bind same site closely associated sites C3b-bearing cells immune adherence negative, indicating is brought about through region molecule not C3d portion. membranes uniformly distributed can move plane. Approximately 4 x 10(5) molecules per cell. had higher affinity than C3b, as shown uptake experiments inhibition rosette formation. Apart from described another specific inactivator-cleaved (C3d) bound red be present cultured in medium containing fresh normal cobra venom factor lysed. Similar results obtained when with serum. lytic effect could abolished inactivating proactivator (C3PA) required C6. It concluded activates system alternate pathway damage cytolysis. postulated destruction this mechanism may play an important role vivo controlling growth.