The polymorphonuclear leukocyte - A new target for erythropoietin

A previous study from our laboratory has shown that erythropoietin (EPO), b eside its traditional role in erythropoiesis, acts as an alleviator of oxid ative stress and inflammation in chronic hemodialysis (HD) patients, confer red in part by activated polymorphonuclear leukocytes (PMNLs), To substanti ate this phenomenon, the existence of EPO receptors (EPO-Rs) on PMNL membra ne was examined at the transcriptional and translational levels, mRNA for E PO-R was detected in PMNLs using specific primers directed towards the extr acellular region of human EPO-R cDNA. The predicted 300-bp fragment was amp lified by reverse transcriptase-polymerase chain reaction. Subcloning and s equence analysis revealed 100% homology of this fragment with human EPO-R, The receptor protein was detected on the surface of intact PMNLs using I-12 5-EpO. Th, protein was further demonstrated by flow cytometric analysis usi ng a fluorescent monoclonal anti-EPO-R. The percentage of PMNLs expressing EPO-R showed a strong correlation with the level of EPO in the serum, sugge sting an upregulation of the receptor by the hormone. Taken together with o ur recent findings that EPO attenuates the oxidative stress and inflammatio n contributed by PMNLs in HD patients, the detection of functional EPO-R ex pression in PMNLs places these cells among the nonerythroid, EPO-responsive target populations. Copyright (C) 2001 S. Karger AG. Basel.