The compatibility of Xenopus antibody and homoiothermic complement

Adult Xenopus laevis serum containing an anti-chicken erythrocyte antibody exhibits complement (C) activity by both the classical and the alternative pathways. Lytic activity is removed by heating serum to 50 degrees C for at least 20 min; it is also removed by polysaccharides and by 7.5 mM EDTA. The optimum temperature for Xenopus C activation is 25 degrees C. The ability of Xenopus antibody against chicken erythrocytes to co-operate with homoiothermic C in in vitro by lysis of chicken erythrocytes was tested. Removal of Xenopus C by heating resulted in apparent damage to the antibody, so C was removed by absorption with antibody/antigen complex. Xenopus antibody will apparently combine with guinea-pig and rat C to effect lysis of chicken erythrocytes; low levels of haemolysis were seen with human, rabbit and chicken sera, while horse and mouse sera were non-lytic. Xenopus C was able to restore the lytic activity of decomplemented rabbit anti-chicken erythrocyte serum.