Red blood cell senescence and neocytolysis in humans after high altitude acclimatization

Abstract A selective lysis of relatively young erythrocytes (neocytolysis), together with a decrease of erythropoietin (EPO) production, has been described in polycythemic, high altitude acclimatized climbers, after descent to sea level, and in astronauts, soon after exposure to weightlessness (Alfrey CP, Rice L, Udden MM, Driscoll TB. Neocytolysis may represent the physiological down-regulation of red-cell mass. Lancet 349 (1997) 1389–90). To study neocytolysis, we analysed blood samples drawn from 4 mountain climbers at sea level before and after 53 days of high altitude acclimatization (≥ 4500 m). After a 6-day descent to sea level, erythropoietin (EPO) plasma levels were lower than before high altitude acclimatization (mean values: 2.5 ± 3.3 versus 10 ± 4.5 mIU/ml, p