New enzyme-linked immunosorbent assay methods for measurement of serum erythropoietin levels and erythropoietin antibodies.

For clinical studies with erythropoietin (EPO), enzyme-linked immunosorbent assays for the determination of EPO and EPO antibodies were developed. Using polyclonal and monoclonal EPO antibodies in a sandwich technique, serum EPO levels greater than 10 pg/ml (corresponding to 1 mU/ml, calibrated with the 2nd WHO IRP EPO) can be determined. In 103 healthy blood donors, a mean (+/- SD) value of 36 +/- 19 pg EPO/ml was found. Very high EPO concentrations were found in patients suffering from myelodysplastic syndrome and aplastic anemia; elevated levels were associated with rheumatoid arthritis and myelomatosis. No EPO antibodies were detectable in EPO-treated patients.