An incompatibility in the reaction of the second component of human complement with the fourth component of guinea-pig complement

Abstract

An incompatibility in the reaction of human C2 with EAC14 consisting of guinea-pig C4 was demonstrated. Human C2 reacted poorly with EAC14 consisting of guinea-pig C4. The substitution of guinea-pig C4 on EAC14 with human C4 resulted in the fifteen- to twenty-fold increase of the haemolytic activity of C2 in whole human serum. It became more manifest in the titration of purified human C2. Purified human C2 showed about 100 times more activity with EAC14 consisting of human C4, although guinea-pig C2 reacted effectively with EAC14 carrying either guinea-pig or human C4. The unsuitability of the measurement of human C2 employing EAC14 prepared with guinea-pig C4 was shown.