MHC-I expression in HTLV-1-positive and -negative cells

The expression level of major histocompatibility class I (MHC-I) and the ex tent of down-regulation of MHC-I after an anti-MHC-I antibody treatment in numerous human T-cell leukemia virus type 1 (HTLV-1)-positive and -negative lymphocytic cell lines were examined. While there was no clear correlation between the expression level of MHC-I and the presence of HTLV-1 genome, a relatively low level of MHC-I down-regulation was generally induced in HTL V-1-positive cells by the antibody. The results may suggest the potential i nvolvement of MHC-I in HTLV-1 leukemogenesis.