The role of cytokines and hematopoietic growth factors in the autocrine/paracrine regulation of inducible hematopoiesis

To elucidate the role of hematopoietic Introduction growth factors (HGFs) and other cytokines in the autocrine or paracrine regulation of inducible hematopoiesis we studied cytokine gene expression in the bone marrow (BM) of patients after myelosuppressive treatment. Furthermore, we studied the cytokine gene expression profile in healthy individuals before and after bone marrow harvesting for the purpose of bone marrow transplantation. We speculated that the bone marrow harvesting procedure might induce changes in cytokine gene expression. No induction of G-CSF, GM-CSF, IL-1 alpha, IL-3, IL-5, IL-8, IL-9, and IL-12 was observed in the BM of patients following intensive chemotherapy. Also, no up-regulation of expression of M-CSF, IL-1 beta, IL-4, IL-6, TNF-alpha, TGF-beta, IGF-1, EDF, and EPA gene was found, illustrating that the investigated cytokines probably are not relevant in the presumed autocrine/paracrine regulation of the recovery of hematopoiesis following depletion of hematopoietic progenitor cells (HPCs). Concomitantly, elevated G-CSF plasma levels were found in these patients, suggesting that G-CSF has an endocrine regulatory role in inducible hematopoiesis. Induction of GM-CSF and IL-8, but not of G-CSF or IL-3 gene expression and upregulation of IL-1 beta and IL-6 gene following BM harvesting was observed. This induction of GM-CSF and IL-8 may be attributed to tissue damage rather than to HPC depletion.