Abstract
Rat C4 from serum and rat C2 from tissue cultures and serum have been measured using different systems. For rat C2 the highest titer was obtained using EAC1gp 4gp and rat C‐EDTA 1:2 with a Tmax of about 10 min. The decay time of EAC1gp 4gp2rat was one log every 40 minutes. For measuring the C4 content of rat serum, rat C‐EDTA only increased the titer twofold over that obtained by using guinea pig C‐EDTA.