Effects of various treatments of bovine complement on its lytic efficacy measured by two different tests.

Bovine complement was treated with various agents known to activate or inactivate one or more of the cascade components. The treated complement was then assessed for remaining hemolytic activity by a tube titration test and a radial hemolysis method. Divalent cation chelators (EDTA and EGTA); immune complexes prepared with serum and IgM, IgG1, IgG2, and IgA isotypes; smooth and rough lipopolysaccharides and lipid A; hydrazine; zymosan; cobra venom factor and brown recluse spider venom caused depletion of complement as determined in the tube titration test. Immune complexes (prepared with serum); hydrazine; cobra venom factor; EDTA and smooth lipopolysaccharide caused loss of hemolytic activity in the radial hemolysis test. This evidence suggests that the radial hemolysis test assessed complement consumed by the alternate pathway, while the tube titration method measured classical pathway consumption.