Human C4-binding protein. Association with immune complexes in vitro and in vivo.
C4-binding protein (bp), a glycoprotein with specific binding affinity for the activated form of C4 (C4b), has recently been isolated from human serum and partially characterized. This report demonstrates that C4-bp is incorporated into soluble immune complexes after complement activation in vitro. The reaction requires Ca++ ions and the presence of C4 in serum. Immunopathological studies of various forms of glomerulonephritis revealed intense C4-bp deposition in glomeruli from patients with immune-complex type of pathogenesis. C4-bp deposition was in close correlation with that of C4. These observations, together with the in vitro association of C4-bp to immune complexes, support the notion that the deposits in glomeruli represent the local accumulation of immune complexes.
D000936:Antigen-Antibody Complex; D001798:Blood Proteins / Q000276:immunology*; D002352:Carrier Proteins / Q000097:blood / Q000276:immunology*; D003181:Complement C4 / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D005921:Glomerulonephritis / Q000276:immunology; D006023:Glycoproteins / Q000097:blood / Q000276:immunology*; D006801:Humans; D007105:Immune Complex Diseases / Q000276:immunology; D066298:In Vitro Techniques
D000936:Antigen-Antibody Complex; D001798:Blood Proteins; D002352:Carrier Proteins; D003181:Complement C4; D006023:Glycoproteins