One of the critical steps in the progression to
cervical cancer appears to be the establishment of persistent human papillomavirus (HPV)
infection. We have demonstrated that the lack of cytotoxic T-lymphocyte response to HPV type 16 (HPV 16) E6
protein was associated with persistence and that the potential presence of dominant CD8
T-cell epitopes was most frequently found (n = 4 of 23) in the E6 16-40 region by examining the pattern of CD8
T-cell epitopes within the E6
protein in women who had cleared their HPV 16
infections. The goal of this study was to define the minimal/optimal amino acid sequences and the HLA restricting molecules of these dominant CD8
T-cell epitopes as well as those of subdominant ones if present. Three dominant
epitopes, E6 29-38 (TIHDIILECV; restricted by the HLA-A0201 molecule), E6 29-37 (TIHDIILEC; restricted by B48), and E6 31-38 (HDIILECV; restricted by B4002), and one subdominant
epitope, E6 52-61 (FAFRDLCIVY; restricted by B35) were characterized. Taken together with a previously described dominant
epitope, E6 52-61 (FAFRDLCIVY; restricted by B57), the CD8
T-cell epitopes demonstrated striking HLA class I binding promiscuity. All of these
epitopes were endogenously processed, but the presence of only two of the five
epitopes could have been predicted based on the known binding motifs. The HLA class I promiscuity which has been described for human immunodeficiency virus may be more common than previously recognized.