IL-2-DEPENDENT HTLV-I-INFECTED T-CELLS ESCAPE FROM NONSPECIFIC, MHC-UNRESTRICTED CELLULAR CYTOTOXICITY

The susceptibility of NK cell-mediated cytolysis was compared between 5 human HTLV-I-transformed T cell lines and 10 newly established IL-8- dependent HTLV-I-infected lines. None of the cell lines were killed af ter 4 hr incubation with normal PBMC. However, after 20 hr, 3 HTLV-I-t ransformed lines were significantly lysed. All the HTLV-I-infected lin es, except 2, weakly inhibited the NK cell-mediated lysis of K562 targ ets. They showed a reduced ability to bind normal PBMC as compared wit h control NK-sensitive T cell lines. The IL-8-dependent lines remained unaffected by PBMC from HTLV-I-infected individuals, including the au tologous donors. In contrast to the HTLV-I-transformed lines, they wer e weakly lysed or not lysed at all by LAK cells and only 5 were killed by ADCC with HTLV-I+ sera and normal PBMC. Taken together, the result s show that IL-8-dependent HTLV-I-infected T cells strongly resist NK cell-mediated cytolysis at a post-binding level and suggest that such cells may escape in vivo from non-specific, MHC-unrestricted cellular cytotoxicity. (C) 1994 Academic Press, Inc.