Measurement of mouse plasma erythropoietin by an improved ELISA

Abstract

We have examined whether mouse plasma erythropoietin (EPO) can be measured by an improved enzyme-linked immunosorbent assay (ELISA) using milk proteins (Block Ace) both as a blocking reagent and as a diluent for standard recombinant human EPO (rHuEPO) and for plasma samples. Block Ace brought about high slope sensitivity of the standard curve, with a low background. The dose-response curves of normal or anaemic mouse plasma and of rHuEPO were linear and parallel to each other. The anaemic plasma had an additive effect with rHuEPO by increasing the absorbance at 405 nm. The coefficients of variation in the intra- and interassays ranged from 4.2% to 15.3%. The plasma EPO levels in 22 normal mice were 18.3±10.3 mU/ml. An inverse relationship 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 show the validity for the use of the new improved ELISA method for measuring circulating murine EPO.