Measurement of mouse plasma erythropoietin by an improved ELISA

We have examined whether mouse plasma erythropoietin (EPO) can be measured by an improved enzyme-linked immunosorbent assay (ELISA) using milk protein s (Block Ace) both as a blocking reagent and as a diluent for standard reco mbinant human EPO (rHuEPO) and for plasma samples. Block Ace brought about high slope sensitivity of the standard curve, with a low background. The do se-response curves of normal or anaemic mouse plasma and of rHuEPO were lin ear and parallel to each other. The anaemic plasma had an additive effect w ith rHuEPO by increasing the absorbance at 405 nm. The coefficients of vari ation in the intra- and interassays ranged from 4.2% to 15.3%. The plasma E PO levels in 22 normal mice were 18.3 +/- 10.3 mU/ml. An inverse relationsh ip between the logarithm of plasma EPO concentrations and blood haemoglobin concentrations, red blood cell counts or packed cell volumes was found in normal mice and in mice with iron deficiency anaemia (IDA). These results s how the validity for the use of the new improved ELISA method for measuring circulating murine EPO.