In vivo expansion of TCR-transduced T cells in partially MHC-mismatched recipients. (A) Flow cytometric analysis of blood samples at day 3 (left) or day 10 (right) after infection from B6 mice that received 1 × 10⁵ OT-I TCR-transduced T cells followed by inflova infection. Activated TCR-transduced T cells can be distinguished from the endogenous Vα2/Vβ5⁺ CD8⁺ fraction by a lower expression of the Vα2/Vβ5 TCR chains. (B-C) Analysis of blood samples from B6 mice (B) and B6*SJL mice (C) that received no modified T cells (top) or 1 × 10⁵ OT-I TCR-transduced T cells (transduction efficiency in B6*SJL mice, 23% of CD8⁺ cells) (bottom) followed by inflova infection. Blood was sampled 5 to 14 days after infection and stained as in panel A. Open circles indicate T-cell responses in individual mice; bars, averages. (D) Flow cytometric analysis of blood samples at day 3 (left) or day 10 (right) after infection from B6*SJL mice that received 1 × 10⁵ F5 TCR-transduced T cells (transduction efficiency, 3.5% of CD8⁺ cells) followed by A/NT/60/68 infection. The percentage of F5 TCR-transduced cells was calculated from the fraction of Vβ11⁺ cells within the population of Vβ-pool⁺ cells. Note that a Vβ11^dull population that is Vβ-pool negative is present in mice that received F5 TCR-modified T cells. This represents TCR-transduced T cells that express an endogenous Vβ chain for which no antibody was available. (E) Analysis of blood samples from B6*SJL mice that received no modified T cells (top) or 1 × 10⁵ F5 TCR-transduced T cells (bottom) followed by A/NT/60/68 infection. Blood was sampled 5 to 14 days after infection and stained as in panel D. Open squares indicate T-cell responses in individual mice; bars, averages.