A new complement function: solubilization of antigen-antibody aggregates.
Antigen-antibody aggregates are solubilized when incubated with fresh serum at 37 degrees, yielding immune-complexes of relatively small molecular weight which contain antigen, antibody, and complement (C3)determinants. Solubilization is complement-dependent,requires free Mg++ but not Ca++, and proceeds in sera from C4- or C5-deficient animals. It is accelerated in the presence of Ca++ in normal or C4-deficient guinea pig serum, suggesting involvement of the Cl-bypass activation of the properdin system. Immune precipitates can also be solubilized by monovalent fragments (Fab) of antibodies directed against determinants of the antibody molecules included in the antigen-antibody lattice. Similarly, it is suggested that complement-mediated solubilization might be induced by the combination of a complement fragment with the antibody in the immune-aggregate.
D000818:Animals; D000906:Antibodies; D000936:Antigen-Antibody Complex; D002118:Calcium / Q000494:pharmacology; D002417:Cattle; D003165:Complement System Proteins; D007140:Immunoglobulin Fab Fragments; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D008274:Magnesium / Q000494:pharmacology; D051379:Mice; D008808:Mice, Inbred CBA / Q000276:immunology; D011817:Rabbits / Q000276:immunology; D012710:Serum Albumin, Bovine / Q000276:immunology; D012711:Serum Albumin, Radio-Iodinated; D012995:Solubility
D000906:Antibodies; D000936:Antigen-Antibody Complex; D007140:Immunoglobulin Fab Fragments; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G; D012711:Serum Albumin, Radio-Iodinated; D012710:Serum Albumin, Bovine; D003165:Complement System Proteins; D008274:Magnesium; D002118:Calcium