Quantitation of CD8(+) T-lymphocyte responses to multiple epitopes from simian virus 40 (SV40) large T antigen in C57BL/6 mice immunized with SV40, SV40 T-antigen-transformed cells, or vaccinia virus recombinants expressing full-length T antigen or epitope minigenes

The cytotoxic T-lymphocyte response to wild-type simian virus 10 large tumo r antigen (Tag in C57BL/6 (H2(b)) mice is directed against three H2-D-h-res tricted epitopes, I, II/III, and V, and one H2-k(b)-restricted epitope, TV, Epitopes I, II/III, and IV are immunodominant, while epitope V is immunore cessive. We investigated whether this hierarchical response was established in vivo or was due to differential expansion in vitro by using direct enum eration of CD8(+) T lymphocytes with Tag epitope/major histocompatibility c omplex class I tetramers and intracellular gamma interferon staining. The r esults demonstrate that epitope IV-specific CD8(+) T cells dominated the Ta g-specific response in vivo following immunization with full-length Tag whi le CD8(+) T cells specific for epitopes I and II/III were detected at less than one-third of this level. The immunorecessive nature of epitope V was a pparent in vivo, since epitope V-specific CD8(+) T cells were undetectable following immunization with full-length Tag, In contrast, high levels of ep itope V-specific CD8(+) T lymphocytes were recruited in vivo following immu nization and boosting with a Tag variant in which epitopes I, II/III, and T V had been inactivated. In addition, analysis of the T-cell receptor beta ( TCR beta) repertoire of Tag epitope-specific CD8(+) cells revealed that mul tiple TCR beta variable regions were utilized for each epitope except Tag e pitope II/III, which was limited to TCR beta 10 usage. These results indica te that the hierarchy of Tag epitope-specific CD8(+) T-cell responses is es tablished in vivo.