Forty-two women attending a colposcopy clinic for evaluation of abnormal cervical cytology and 13 normal controls were studied for the presence of lymphocyte proliferation (LP) cell-mediated immune (CMI) responses and serological reactivity to E7 peptides of human papillomavirus type 16 (HPV-16). HPV was typed by Southern blot hybridization of exfoliated cervicovaginal cell DNA. Positive LP responses (stimulation index > or = 5.0) to one or more E7 peptides were observed in 28.6% (12 of 42) of patients and 23.1% (three of 13) of controls. Of patients infected with HPV-16, -31 or -33, 63.6% (seven of 11) showed a positive LP response compared with 14.3% (two of 14) of women infected with other HPV types (P = 0.02), 17.6% (three of 17) negative for HPV (P = 0.02) and 23.1% (three of 13) of controls (HPV status unknown) (P = 0.05). C-terminal peptide 109 (amino acids 72 to 97) elicited positive LP responses in 45.4% (five of 11) of patients infected with HPV -16, -31 or -33 compared with 7.1% (one of 14) patients infected with other HPVs (P = 0.04), 5.9% (one of 17) of women negative for HPV (P = 0.02) and 7.7% (one of 13) of controls (P = 0.05). HPV-16 group-specific LP responses of borderline significance were also observed against E7 peptides 103, 105 and 108 (17-37, 37-54 and 62-80) (P = 0.07). ELISA reactivity (IgG) to E7 peptide 109 (72-97) was present in 7.7% (one of 13) of controls, 35.3% (six of 17) of HPV-negative patients, 42.9% (six of 14) of patients infected with other HPVs, and only 9.1% (one of 11) of patients infected with HPV-16, -31 or -33. CMI responses to C-terminal HPV-16 E7 peptide 109 (72-97) were thus significantly related to ongoing cervical infection with HPV-16 and closely related types, whereas serological reactivity to E7 peptides was not HPV type-specific.