Anticomplementary activity of liver disease sera

Anticomplementary activity (ACA) of five liver disease sera with no hemolytic complement activity and one IgG-myeloma serum was examined before and after heating at 56°C for 30 min. The ACA of IgG-myeloma serum was found only in the heated sample. However, the ACA of liver diseases sera was found in both unheated and heated samples. Since ACA of liver disease sera was inhibited by rheumatoid arthritis serum but not by normal serum, IgG antibodies combined with some antigen or aggregated IgG were suspected as factors eliciting the ACA. They might participate also in decreasing of hemolytic complement activity in the cold, which was frequently found in chronic liver disease sera.