Fratricide among CD8(+) T lymphocytes naturally infected with human T celllymphotropic virus type I

Infection and gene expression by the human T lymphotropic virus type I (HTL V-I) in vivo have been thought to be confined to CD4(+) T lymphocytes. We s how here that, in natural HTLV-I infection, a significant proportion of CD8 (+) T lymphocytes are infected by HTLV-I. Interestingly, HTLV-I-specific bu t not Epstein-Barr virus-specific CD8(+) T lymphocytes were shown to be inf ected. Furthermore, HTLV-I protein expression in naturally infected CD8(+) T lymphocytes renders them susceptible to fratricide mediated by autologous HTLVI-specific CD8+ T lymphocytes. Fratricide among virus-specific CTLs co uld impair the immune control of HTLV-I and possibly other lymphotropic vir uses.