Human T cell responses to HPV 16 E2 generated with monocyte-derived dendritic cells

Persistent infection with human papillomavirus (HPV) type 16 has been impli cated in the etiology of cervical cancer. The E2 protein is required early in viral infection and therefore may serve as a useful immune target for a vaccine aimed at prevention or therapy of premalignant lesions. Dendritic c ells (DC) prepared from monocytes and pulsed with bacterially produced HPV 16 E2 C-terminus protein were used to stimulate autologous T cells over sev eral rounds of stimulation. T cells were tested for gamma -interferon relea se by ELISPOT and for cytotoxic activity by (51)chromium release assays. To generate E2-expressing target cells for cytotoxicity assays, we constructe d a recombinant vaccinia virus encoding HPV 16 E2, which was used to infect autologous Epstein-Barr virus-transformed lymphoblastoid cell lines (LCL). The results show that DC pulsed with E2 C-terminus protein induce gamma -i nterferon-releasing T cells as demonstrated by ELISPOT. Furthermore, we dem onstrate E2-specific lysis of vaccinia-E2 infected autologous LCL by CD8+ c ytotoxic T lymphocytes (CTL). E2-specific CTL did not lyse untreated autolo gous LCL or LCL infected with wild-type vaccinia and showed low levels of c ytotoxicity against natural killer cell-sensitive K562 cells. In addition, T cells stimulated with DC in the absence of E2 failed to demonstrate lysis of vaccinia-E2-labeled targets. Phenotypically, CTL populations were CD3+/ CD8+. These results will facilitate the study of naturally occurring T-cell responses to HPV E2 in patients with cervical intraepithelial neoplasia an d the development of immunotherapeutic strategies designed to treat this an d other HPV-associated diseases. (C) 2001 Wiley-Liss, Inc.