INFECTION AND CELLULAR ACTIVATION BY HUMAN T-CELL LEUKEMIA VIRUSES, TYPE-I AND TYPE-II

Resting peripheral blood mononuclear cells (PBMC) or purified T-cells can be induced to proliferate when cocultured in vitro with fixed HTLV -infected T-cells. This process of HTLV-dependent cellular activation and induction of proliferation has been considered distinctive because of an apparent independence from conventional T-cell costimulatory si gnals. We have examined several HTLV-infected cell lines and found tha t proliferation was readily induced in resting PBMC by T-cells that we re productively-infected with HTLV. However, equivalent HTLV-productiv e infection in a B-cell line failed to induce proliferation in PBMC, s uggesting that HTLV-dependent induction of proliferation in PBMC was, at least in part, dependent upon a T-cell-specific signal. Furthermore , the induction of proliferation in PBMC populations was found to over lap with, and actually require, transfer and establishment of HTLV inf ection within the T-cell compartment of the PBMC population. These fin dings suggest that virus-induced activation of target cells may be dir ectly associated with transfer and spread of HTLV infection. (C) 1996 Academic Press, Inc.