HLA class II restriction pattern and peptide sequence of a pp65-derived epitope in a seropositive individual with uncommon HLA type after generation of CMV-specific T cells with complete pool. T cells of an individual with HLA-type A*26JV, A*29BD and B*44CU, B*O8DKG, DRB1*1301, DRB1*1501 were generated as previously described. (A) PBMCs pulsed with pentadecapeptide pools 8, 9, 23 and complete pool induced significant intracellular IFN-γ production of CD4⁺ cells in this individual. All other pentadecapeptide pools failed to induce a response. (B) Only pentadecapeptides 128 and 129, encoded in pool 23, stimulated T cells effectively. The neighboring pentadecapeptide pools 127 and 130, as well as all other pentadepeptides contained within pool 23 (not shown), did not induce intracellular IFN-γ production. Based on the overlapping principle, the amino acid sequence F FWDAN DIYRI represented within pentadecapeptide 128 and 129 likely contains the candidate peptide being recognized by the T cells of this individual. (C) HLA restriction of this pentadecapeptide was analyzed by pulsing EBV-BLCLs, each expressing one of the individual's HLA allele only. BLCLs encoding the HLA-DRB1*1301 allele were lysed after pulsing with the KYQEF FWDAN DIYRI peptide or after infection with CMV virus, whereas the EBV-BLCLs expressing the other alleles pulsed with the same peptide did not induce any cytotoxic T-cell responses.