INTRARENAL EXTRAMEDULLARY ERYTHROPOIESIS IN RENAL-ALLOGRAFT FINE-NEEDLE ASPIRATES

Recombinant human erythropoietin (rhEPO) is widely used in patients wi th end-stage renal disease and occasionally in renal allograft recipie nts to correct anemia. Red blood cell production is markedly increased by rhEPO; however, no extramedullary erythropoiesis (EME) has been as sociated with this hormone. We observed intrarenal EME in five allogra ft fine-needle aspirates performed for reduced graft function in four patients between 3.7 and 7 weeks following transplantation. These four patients received rhEPO during dialysis and three resumed rhEPO thera py after transplantation; all four remained anemic. Donors were betwee n 13 months and 13 years of age, with one pediatric and three adult re cipients. Aspirates with apparently incidental EME contained all stage s of red blood cell precursors, but these cells were not observed in c orresponding peripheral blood samples. The hematopoietic cells could b e readily distinguished from cells of lymphoid origin. There were no c orrelations between intragraft EME and aspirate or clinical diagnosis referable to renal dysfunction. Aspirates performed prior to 3.7 weeks or after 7 weeks did not demonstrate EME. These data suggest that end ogenous EPO and rhEPO in anemic patients receiving pediatric renal all ografts may activate red blood cell precursors in the young graft, ind ucing intrarenal EME. Recognition of this entity is important to disti nguish it from immune activation or malignancy within the donor organ. (C) 1995 by the National Kidney Foundation, Inc.