The Effect of Heat-Treatment on the Estimation of Bioactive Erythropoietin in Serum using the Mouse Spleen Cell Assay

Human serum is toxic to in vitro assays for erythropoietin (Ep), including the mouse spleen cell assay. This effect is mediated by complement-dependent IgM heteroantibodies and can be overcome by heating the serum at 56°C for 30 min. Heat-treatment causes a loss of serum Ep and a shift of activity to two peaks of higher molecular weight. The enhanced activity of certain proteases and glycosidases during the heat-treatment is probably responsible for the observed loss and shift of serum Ep activity.