The Effect of Unheated Bovine Serum on the Complement-Fixing Activity of Heat-Inactivated Bovine Antiserum with Homologous Antigen. V. Residual Complement Activity.

Complement-fixation tests of three different antigen-bovine antibody systems, two antibacterial and one antiviral, were set up with or without normal bovine serum supplement. At the end of the fixation period all mixtures were tested for whole complement activity and for first, second, third and fourth complement components using the conventional, crude reagents R1, R2, R3 and R4. The increased fixation in mixtures containing the bovine serum supplement mainly reflected a greater decrease in second and fourth component activity than in the antigen-bovine antibody mixtures with non-supplemented complement. The decline in first component activity was relatively less. The results of tests for residual third component activity were not consistent.