The in vitro effect of high‐dose recombinant human erythropoietin on granulocyte‐macrophage colony production in premature infants using a defined serum deprived cell culture system

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Abstract
Recent reports of neutropenia associated with the use of recombinant human erythropoietin (r‐HuEpo) in preterm infants with the anaemia of prematurity have raised concern over the clinical use of this hormone. The present studies were undertaken to determine whether high‐dose r‐HuEpo has an effect on granulocyte production in vitro. The studies used a serum deprived, optimized semi‐solid cell culture system to investigate the effect of lineage specific and non‐specific granulocyte and erythroid colony stimulating factors on circulating peripheral blood granulocyte‐macrophage colony forming units (CFU‐GM), erythroid burst forming units (BFU‐E) and multilineage colonies (CFU‐Mix) from nine premature infants and seven healthy adults. CFU‐GM were grown in the presence of interleukin 3 (IL3) 8 ng/ml, granulocyte‐macrophage colony stimulating factor (GM‐CSF) 20 ng/ml and granulocyte colony stimulating factor (G‐CSF) 15 ng/ml alone and combinations of G‐CSF with GM‐CSF or IL3. The number, size and differentiation of CFU‐GM colonies were then analysed in the presence and absence of high dose r‐HuEpo (4 U/ml).High‐dose r‐HuEpo did not exert any significant modulatory effects on the number of CFU‐GM colonies produced in the presence of IL3, GM‐CSF and G‐CSF alone or in combination. The number of cells within each CFU‐GM colony did not change significantly, nor was there a significant change in the degree of differentiation. The combined number of BFU‐E. CFU‐GM and CFU‐Mix colonies increased with r‐HuEpo in both adults (1·8x) and preterm infants (1·4x), almost exclusively due to an increase in BFU‐E derived colonies. Thus, no evidence was found for an r‐HuEpo mediated redirection of multipotential haemopoietic stem cells into committed erythroid precursors at the expense of myeloid precursors.