EFFECTS OF REPEATED ADMINISTRATION OF GRANULOCYTE-COLONY-STIMULATING FACTOR (G-CSF) ON NEUTROPHIL COUNTS, PLASMA CYTOKINE, AND CYTOKINE RECEPTOR LEVELS

Granulocyte colony-stimulating factor (G-CSF) induces the release of m ature neutrophils from storage pools and stimulates differentiation of myeloid progenitor cells, Recently, it has been shown that a standard dose of G-CSF induces immunophenotypical and functional changes of ne utrophils that persist for 1 week, The authors investigated the effect s of 300 mu g of G-CSF administered subcutaneously twice, 1 week apart , to 10 healthy volunteers, on neutrophil and monocyte counts and on t he plasma levels of interleukin 1 receptor antagonist (IL-1ra), tumour necrosis factor-alpha (TNF-alpha), soluble TNF receptor (sTNF-r) p55 and p75, G-CSF on both occasions increased neutrophil and monocyte cou nts and the plasma levels of all cytokines and cytokine receptors meas ured, All parameters assessed had returned to baseline prior to the se cond administration of G-CSF, The increases in neutrophil counts and p lasma IL-1ra levels were larger following the second injection, wherea s the increase in plasma sTNF-r p75 levels was smaller, G-CSF induced increases in monocyte counts, TNF-alpha and sTNF-R p55 levels did not differ between the first and second injection, Our finding of an incre ased response of healthy humans to a second G-CSF challenge 1 week fol lowing a first one may be due to long-lasting increases in storage poo l neutrophils. (C) 1996 Academic Press Limited