Augmented functional activity of CMVpp65CTLs responding to pentadecapeptides containing overlapping epitopes presented by HLA class I and class II alleles. Comparison of IFN-γ CD3⁺ T-cell responses to the CMVpp65 15-mer peptide pool in CMVpp65CTLs derived from donors who coinherited both the class I and class II HLA alleles presented epitopes in an overlapping 15-mer peptide vs responses in donors generating both CD4⁺ and CD8⁺ T cells to CMVpp65 peptides that do not overlap or to individuals generating only a CD8⁺ CMVpp65–specific T-cell response.