In vitro and in vivo studies with purified recombinant human interleukin 5.

The functional activities of highly purified recombinant human IL 5 (hIL 5) have been characterized on a number of cell types in vitro and in BALB/c mice in vivo. In vitro, hIL 5 could induce the differentiation of eosinophils from precursors in both human and mouse bone marrow with approximately the same efficiency. A mouse IL 5/3-dependent B cell line, LyH7.B13, was found to proliferate in response to hIL 5 but not human interleukin 1 (IL 1), interleukin 2 (IL 2), interleukin 3 (IL 3), interleukin 4 (IL 4), interleukin 6 (IL 6), interferon-gamma (IFN-gamma), or granulocyte macrophage-colony stimulating factor (GM-CSF) and was at least 10-fold more sensitive than BCL1 mouse lymphoma cells. We have successfully used this cell line to demonstrate the production of IL 5 by human T cell clones. In marked contrast to its effects on murine B cell lines, hIL 5 had no demonstrable activity on CD23 expression, anti-mu costimulated proliferation or IgM, IgG, or IgE production by tonsillar B cells and did not influence such responses triggered by IL 4. BALB/c mice injected with hIL 5 for 7 consecutive days were shown to develop an eosinophilia comparable to that induced by infection with the parasite Mesocestoid corti.