IDENTIFICATION OF A NOVEL APOPTOSIS-INDUCING FACTOR DERIVED FROM LEUKEMIC-CELLS - ENDOTHELIAL INTERLEUKIN-8, BUT NOT MONOCYTE-DERIVED, INDUCES APOPTOSIS IN LEUKEMIC-CELLS

The human myelogenous leukemia cell line HL-60, treated with phorbol 1 2, 13-dibutyrate (PDBu), produces apoptosis-inducing factors (AIFs) in leukemic cells. We have purified AIF against leukemic cell line K562 as target cells, and N-terminal amino acid sequencing analysis reveale d that this purified protein is identical to endothelial cell-derived interleukin 8 ([(Ala)-IL-8](77)). In Western blot analysis of supernat ants of PDBu-treated HL-60 cells,only [(Ala)-IL-8](77) was detected. M oreover, recombinant human [(Ala)IL-8](77) induced apoptosis in leukem ic cell lines such as K562, HL-60, KG-1, U937, THP-1 and Jurkat, but m onocyte-derived IL-8 ([(Ser)-IL-8](72)) did not. Therefore [(Ala)-IL-8 ](77) plays an important role in inducing apoptosis against leukemic c ells and may lead to a new therapy for leukemia. (C) 1998 Academic Pre ss.