Antigenic interspecies cross-reaction of subcomponent C1q of the first component of complement: evidence for its cross-reaction in both collagen-like and non-collagen-like regions.
Human, bovine, and mouse C1q, a subcomponent of the first complement component, were purified, and both globular (GF) and collagen-like fragments (CLF) were isolated from human and bovine C1q. Antisera were produced in rabbits with these C1q or fragments, and F(ab')2 of immunoglobulin G (IgG) was purified from the antisera in order to avoid the possible non-specific binding of C1q of these animals to the Fc portion of rabbit IgG. Immunodiffusion analyses and radioimmune inhibition tests with these F(ab')2 showed that the definitive antigenic cross-reactivity was among C1q molecules of these animals, and that the regions participating in interspecies cross-reactions were located in both GF and CLF of C1q. These results suggest that both the C-terminal non-collagenous globular and the N-terminal collagen-like domains of C1q molecules may have remained highly conserved during evolution.
D000818:Animals; D002417:Cattle; D003094:Collagen / Q000276:immunology*; D003166:Complement Activating Enzymes / Q000276:immunology*; D003172:Complement C1 / Q000276:immunology*; D015922:Complement C1q; D003429:Cross Reactions; D006801:Humans; D005779:Immunodiffusion; D007074:Immunoglobulin G / Q000032:analysis; D051379:Mice; D011817:Rabbits / Q000276:immunology; D013045:Species Specificity
D003172:Complement C1; D007074:Immunoglobulin G; D015922:Complement C1q; D003094:Collagen; D003166:Complement Activating Enzymes