Hematopoietic Growth Factors Are Differentially Regulated in Monocytes and CD4+ T Lymphocytes: Influence of IFN-α and Interleukin-4

ABSTRACT We investigated the influence of interferon-α (IFN-α) on the synthesis of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3) by monocytes and activated T helper cells. IFN-α inhibited the production of GM-CSF in unstimulated and lipopolysaccharide (LPS)-activated monocytes to the same extent as was observed in the presence of IL-4. In highly purified CD4+ T cells, which were activated by incubation with immobilized anti-CD3 antibody and anti-CD28, IFN-α reduced production of GM-CSF to 47%. In contrast, GM-CSF production in activated T cells was unaffected by exogenously added IL-4. The production of IL-3 by T helper cells was significantly inhibited by IFN-α as well. IL-3 production by CD3/CD28-stimulated T helper cells was exclusively enhanced by IL-4. The exogenous addition of IL-4 led to a highly significant increase of IL-3 levels in T cell supernatants to 231% of control cultures (range 137%–605%), whereas other T cell-derived cytokines, such as IFN-γ and IL-1...