AbstractThe cell‐mediated and humoral immune responses to human papillomavirus (HPV) were tested in groups of patients with various degrees of cervical intraepithelial neoplasia (CIN) using a lymphocyte proliferation assay (LPA) as a measure of circulating sensitised T‐cells and an enzyme‐linked immunosorbent assay (ELISA) for antibodies.Twenty‐three of 92 patients (25%) gave stimulation indices (S.I.) greater than two to at least one of the several antigen preparations tested in the LPA. Of 282 patients, 144 (50.1%) showed ELISA indices (E.I.) greater than one to HPV‐1 and/or HPV‐2 antigens prepared by disruption of purified virions.No correlation was found between positive responses in either test and the presence in cervical biopsies of koilocytes (considered pathognomonic for HPV infections), or between positive responses and the degree of dysplasia observed. Rather, positive antibody and T‐cell responses corresponded with a history of past or present skin warts. Although antibody was detected in 42/86 (48.8%) women who thought they had never had warts, only 2/24 (8.3%) with no known history gave a positiv