PROLIFERATIVE T-CELL RESPONSES TO HUMAN PAPILLOMAVIRUS TYPE-16 L1 PEPTIDES IN PATIENTS WITH CERVICAL DYSPLASIA

Human papillomavirus type 16 (HPV-16) can cause genital warts, cervica l dysplasias and carcinoma of the cervix. Cell-mediated immunity is th ought to be important in protection against the virus and in its elimi nation, but little is known about the mechanisms involved. In a cross- sectional study we have demonstrated proliferative T cell responses to peptides representing the HPV-16 L1 capsid protein (aa 199-409) in th e peripheral blood of 63% of patients (n = 41) with histological evide nce of cervical dysplasia and in 45% of healthy age-matched controls ( n = 11). This was achieved by generating short-term T cell lines (STLs ) from each individual in vitro against a beta-galactosidase-HPV-16 L1 (aa 199-409) fusion protein for 2 weeks, and then identifying the HPV epitopes they recognized with overlapping synthetic peptides (15-mers ) spanning this region in 3 day specificity assays. Histological gradi ng and HPV typing by PCR were performed on patients' cervical biopsies taken at the same clinical visit as the peripheral blood samples. An immunogenic region was identified between aa 311-345 in 73% of patient s (18% in controls) who responded to HPV-16 L1 (aa 199-409). The numbe r of responders to this region was significantly higher in patients wi th HPV-16-positive biopsies when compared to those with HPV-16-negativ e biopsies (P = 0.006), as was the number of responders to individual peptides 311-325 (NLASSNYFPTPSGSM; P = 0.04) and 321-335 (PSGSMVTSDAQI FNK; P = 0.004) representing this region. The mean level of response t o each individual peptide was also higher in the patient group than th e controls (P < 0.05). The most significant finding was that all patie nts with evidence of a current HPV-16 infection responded to one or mo re L1 peptides (P = 0.0004) and 92% had high grade cervical intraepith elial neoplasia (CIN III). We also found that the CIN III group was mo re likely to respond to any L1 peptide than either the atypical group (P = 0.04) or the controls (P = 0.05). Data from four individuals show ed that the majority of peptide-specific STLs were CD4(+) but some CD8 (+) STLs were also detected.