Effects of cytokines from virus-induced human lymphoblasts on the growth and viability of the promyelocytic leukemia cell line HL-60.

Cells of the human B-cell lymphoblastic leukemia line, BALL-1, were stimulated with Sendai virus. It is shown that the crude culture supernatants contain not only interferon-alpha (IFN-alpha) and tumor necrosis factor-alpha (TNF-alpha) but also other cytokines, here collectively termed 'X' cytokines. The latter did not affect the cytostatic or differentiation-inducing effect of IFN-alpha but synergistically increased the cytotoxicity of TNF-alpha.