title: Elimination of terminal complement intermediates from the plasma membrane of nucleated cells: the rate of disappearance differs for cells carrying C5b-7 or C5b-8 or a mixture of C5b-8 with a limited number of C5b-9.
abstract: We have previously shown that multiple complement (C) channels are required for lysis of a nucleated cell in contrast to the single channel requirement for erythrocytes. To further investigate this multichannel requirement for nucleated cells, we examined the stability of terminal C complexes in the plasma membrane of Ehrlich ascites tumor cells. Ehrlich cells bearing C5b-7 or C5b-8 with or without C9 were incubated at 37 degrees C or 0 degree C for various time intervals before converting the remaining complexes to lytic C5b-9 channels. C5b-7, C5b-8, and C5b-8 in the presence of a limited number of C5b-9 complexes disappeared functionally from the plasma membrane at 37 degrees C, with initial half-lives of 31, 20, and 10 min, respectively. Disappearance of these complexes did not occur at 0 degree C, nor did disappearance occur at 37 degrees C when formed on sheep erythrocytes. The fate of C5b-8 complexes on the surface of Ehrlich cells was traced with colloidal gold particles bound to C5 determinants on C5b-8 with the use of immunoelectron microscopy. Colloidal gold could be seen on the cell surface after specific binding to cells carrying C5b-8 sites at 0 degree C. After incubating these cells at 37 degrees C, gold particles were internalized into the cell continuously via endocytic vesicles. It is postulated that terminal C complexes may stimulate or accelerate the removal of these complexes from the cell surface.
mesh_terms: D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000276:immunology / Q000378:metabolism* / Q000648:ultrastructure; D002462:Cell Membrane / Q000276:immunology / Q000378:metabolism / Q000648:ultrastructure; D003186:Complement C9 / Q000502:physiology; D015938:Complement Membrane Attack Complex; D003165:Complement System Proteins / Q000032:analysis / Q000378:metabolism*; D004306:Dose-Response Relationship, Immunologic; D004355:Drug Stability; D004912:Erythrocytes / Q000378:metabolism; D006046:Gold; D006461:Hemolysis; D006801:Humans; D007700:Kinetics; D051379:Mice; D011817:Rabbits
chemical_list: D003186:Complement C9; D015938:Complement Membrane Attack Complex; D006046:Gold; D003165:Complement System Proteins