CD4-positive and CD8-positive cytotoxic T lymphocytes contribute to human papillomavirus type 16 E6 and E7 responses

Cytotoxic T-lymphocyte (CTL) responses to E6 and E7 were previously shown t o be more commonly detectable in human papillomavirus type 16 (HPV-16)-posi tive women without squamous intraepithelial neoplasia (SIL) than in HPV-16- positive women with SIL (M, Nakagawa, D, P, Stites, S, Farhat, J, R, Sisler , B, Moss, F, Kong, A. B, Moscicki, and J, M, Palefsky, J, Infect. Dis, 175 :927-931, 1997), The objective of this study was to characterize the phenot ype(s) of the effector cell population responsible for IIPV-16 E6- and E7-s pecific cytotoxic responses. Peripheral blood mononuclear cells were stimul ated with HPV-16 E6 or E7 fusion protein. Cells from an autologous B-lympho blastoid cell line, infected with vaccinia virus expressing EG or E7, serve d as target cells. The effector cells were characterized by using natural-k iller-cell removal, antibody blocking, and T-cell subset separation. Our re sults suggest that both CD4 and CD8 T lymphocytes contribute to HPV-16 E6- and E7-specific CTL responses although their relative contributions vary fr om individual to individual. On the other hand, natural killer cells in the effector cell population contribute to background activities but not to HP V-specific responses in this assay system.