The influence of the supernatant obtained from a culture of IL-2-activated lymphocytes on human hematopoietic progenitors.

A supernatant obtained from the culture of recombinant human interleukin 2-activated lymphocytes was added to granulocyte (G)-, macrophage (M)-, and granulocyte-macrophage (GM)-progenitor assays using a plasma clot culture method. The supernatant was found to exert a suppressive influence on the colony and cluster formations of the G progenitors. This suppressive influence of the supernatant was almost completely neutralized by the addition of a combination of anti-human tumor necrosis factor alpha (HuTNF-alpha) and anti-human interferon gamma (HuIFN-gamma) antibodies, and it has been speculated that this suppressive influence of the supernatant is probably due to TNF-alpha and IFN-gamma. The numbers of M and GM progenitors increased remarkably in the assays in which the supernatant was added when compared to assays without the supernatant; this suggests that these progenitors were resistant to TNF-alpha and IFN-gamma. Among the bone marrow mononuclear cells (BMNC) excluding erythroid-rosette-forming (ERFC) or adherent cells, the influence of the supernatant on these progenitors was not significantly different. The results of our study have shown that ERFC and the adherent cells in BMNC hardly affected the appearance of the suppressive influence.