Membrane-attack complexes and membrane complement inhibitors on leukocyte surface during combined exposure to meningococcal lipopolysaccharide and complement

Abstract

Leukocytes from donors and subjects with terminal complement component deficiency were incubated for 30 rain at 37~ in autologous serum with or without meningococcal lipopolysaccharide (LPS), followed by treatment with monoclonal antibodies to membrane-attack complexes (MAC) and complement inhibitors and cytofluorometry. After incubation in normal serum, about 97% granulocytes and 65% lymphocytes expressed CD55 and CD59. MAC were detected on only 5% of both types of cells. After incubation with the serum and meningococcal LPS, up to 40% granulocytes expressed MAC, expression of CD55 was decreased, and of CD59 virtually did not change. MAC were not detected in cells incubated in the serum with terminal complement component deficiency. LPS-dependent MAC-mediated hyperactivation of granulocytes may play an unfavorable role in meningococcal infection.