title: In vivo modulation of rat complement activities by infusion of anti-H antibodies.
abstract: Regulation of the activity of the alternative pathway of complement occurs by the plasma proteins I and H. H is able not only to prevent formation of the amplification convertase C3bBb but also to cause the decay-dissociation of Bb from C3bBb. The present studies have investigated the role of H in vivo. Affinity-purified goat (Fab')2-anti H was infused intravenously in rats, and its effect on C4, C3 and CH50 activities was assessed. In addition, H, C3, C4 and B were quantitated by immunochemical methods. H depletion was dependent on the dose of anti-H, and maximal consumption in vivo occurred between 5 and 15 min. A maximum of 51% and 77% hemolytic C3-consumption was seen after 15 min with 3.8 and 8.4 mg anti-H, respectively. The injection of 6.3 mg affinity-purified goat IgG anti-rat H caused 96.8 +/- 0.7% and 85.0 +/- 1.4% consumption of CH50 and C3 hemolytic activity, respectively. Using this dose of IgG anti-rat H, it was found that the clearance in rats of rat erythrocytes sensitized with 8000 molecules of guinea pig IgG2 per E was impaired as compared to the clearance of these intermediates in control rats injected with a comparable dose of normal goat IgG. The results indicate that H functions as a potent regulator of C in vivo and that infusion of anti-H can be used as a method to achieve depletion of circulating complement components.
authors.forename: R
authors.initials: R
authors.lastname: Veerhuis
authors.forename: L A
authors.initials: LA
authors.lastname: van Es
authors.forename: M R
authors.initials: MR
authors.lastname: Daha
mesh_terms: D000818:Animals; D000906:Antibodies; D003167:Complement Activation; D003172:Complement C1 / Q000378:metabolism; D003176:Complement C3 / Q000378:metabolism; D003180:Complement C3b Inactivator Proteins / Q000276:immunology*; D003181:Complement C4 / Q000378:metabolism; D011415:Complement Factor B / Q000378:metabolism*; D017242:Complement Factor H; D003170:Complement Pathway, Alternative; D003165:Complement System Proteins / Q000378:metabolism*; D004792:Enzyme Precursors / Q000378:metabolism*; D006461:Hemolysis; D008099:Liver / Q000378:metabolism; D051381:Rats
chemical_list: D000906:Antibodies; D003172:Complement C1; D003176:Complement C3; D003180:Complement C3b Inactivator Proteins; D003181:Complement C4; D004792:Enzyme Precursors; D017242:Complement Factor H; D003165:Complement System Proteins; D011415:Complement Factor B