Effect of Human Recombinant Interleukin 4 on In Vitro Granulopoiesis of Human Bone Marrow Cells

Abstract

Utilizing in vitro colony assay, we investigated the effect of human recombinant interleukin 4 (hIL-4) on granulopoiesis of normal human bone marrow cells. Though hIL-4 itself did not possess any colony-stimulating activity, the number of neutrophil (N) colonies, particularly the number of small colonies, supported by human recombinant G-CSF (hG-CSF) was significantly increased when hIL-4 was used as a costimulant. In contrast, the number of eosinophil (Eo) colonies supported by hlL-5 was decreased when hIL-4 was used as a costimulant. Also, the numbers of N and Eo colonies supported by hIL-3 or hGM-CSF were both significantly decreased when hIL-4 was added. These data suggest that hIL-4 has diverse positive and negative regulatory effects on human neutro- and eosinophilopoiesis as a cofactor of various CSFs.