THE COMPLEMENT-SYSTEM OF CALOMYS-CALLOSUS, RENGGER, 1830 (RODENTIA, CRICETIDAE)

The complement system (C) of Calomys callosus, Rengger, 1830 (Rodentia , Cricetidae), a wild reservoir for several infectious agents in Latin America, was characterized. Sera from normal adult animals lysed shee p erythrocytes (E(s)) previously sensitized with rabbit serum anti-E(s )(A(r)) in the presence of veronal-buffered saline containing 0.15 mM CaCl2 and 0.5 mM MgCl2, pH 7.4, or unsensitized rabbit erythrocytes (E (r)) in the presence of one-half isotonic strength veronal-buffered-sa line containing 2.5% glucose, 2 mM MgCl2 and 10 mM EGTA, pH 7.4. Both hemolytic curves were sigmoidal in shape, with CH50 values of 30-40 fo r females and 20-30 for males. C5, determined hemolytically using the intermediate cells E(s)A(r)C1m4m2m3m, was approximately 4.5 x 10(8)/ml 4.0 x 10(8)/ml for females and males, respectively. Immunochemical se rum analyses by double immunodiffusion or by immunoblotting using poly clonal antisera against human C1s, C1q, C2, C3, C4, C5, C8 and factors B, I and H indicated that C. callosus C components factor B, C4 and C 3 cross-reacted with the corresponding human C components. Thus, C. ca llosus was found to contain effective classical and alternative pathwa ys (CP, AP) and common pathways, reasonable amounts of C5 and common e pitopes in the key C components, factor B, C4 and C3, which were prese rved during evolution.