“…Hence, upregulation of HTLV-1 expression has been linked to T cell activation events mediated via PKC expression. However, despite the constitutive expression of IL-2R (Depper et al, 1984;Popovic et al, 1983;Yodoi et al, 1983) and in some cases the production of IL-2 (Depper et al, 1984;Gootenberg et al, 1981;Hattori et al, 1981) by circulating HTLV-1-infected T lymphocytes in vivo, HTLV-1 gene products are expressed at low levels (Franchini et al, 1984;Hoshino et al, 1983;Sugamura et al, 1984). Viral regulatory protein transcripts have been detected using reverse transcriptase PCR in lymphocytes of HTLV-1-infected patients, but expression is low and occurs in only a small number of cells (Gessain et al, 1991; 0001-2241 © 1994 SGM Kinoshita et al, 1989).…”