Class I-unrestricted noncytotoxic anti-HTLV-I activity of CD8(+) T cells

Although it is widely believed that viral clearance is mediated principally by the destruction of infected cells by cytotoxic T cells, noncytolytic an tiviral activity of CD8(+) T cells may play a role in preventing the progre ssion to disease in infections with immunodeficiency viruses and hepatitis B virus. We demonstrate here that (1) replication of human T-lymphotropic v irus type I(HTLV-I) is more readily detected from CD8(+) T-cell-depleted (C D8(-)) peripheral blood mononuclear cells (PBMCs) of healthy HTLV-I carrier s than from unfractionated PBMCs, (2) cocultures of CD8(-) PBMCs with autol ogous or allogeneic CD8(+) T cells suppressed HTLV-I replication, and (3) C D8(+) T-cell anti-HTLV-1 activity is not abrogated in trans-well cultures i n which CD8(+) cells are separated from CD8(-) PBMCs by a permeable membran e filter. These results suggest that class I-unrestricted noncytolytic anti -HTLV-l activity is mediated, at least in part by a soluble factor(s), and may play a role in the pathogenesis of HTLV-I infection. (C) 2000 by The American Society of Hematology.