FIGURE 4. Hematopoietic MHCI dependent OTI IMP CD8⁺ T cells exhibit prompt and potent antigen specific response in vitro without primary antigen exposure.

BMTs were done as indicated and donor TCR transgene positive CD8α⁺ cells from OTI→WT (CD45.2⁺MHCI⁺), MHCI^−/−OTI→WT (CD45.2⁺MHCI⁻) and OTI→MHCI^−/− (CD45.2⁺MHCI⁺) chimeras analyzed. (A) Flow cytometric analysis of CD8⁺ T cells for CD44 and CD122 and P/I induced IFN-γ production in chimeric spleens. (B) Percentages and numbers of CD44^hiCD122⁺ IMP CD8⁺ T cells, CD44^loCD122⁻ naïve CD8⁺ T cells, and proportion of CD44^hi IFN-γ producing cells in response to P/I. *p < 0.05, ns = not significant, by Student’s t test. Data represent results from three independent experiments. (C) Percentages of CD44^hi IFN-γ⁺, CD44^hi TNF-α⁺ and IFN-γ⁺/TNF-α⁺ double positive donor CD8⁺ T cells in response to OVA and OVA_257–264 peptide along the time course. All values were corrected for the response of non-stimulated controls. *p < 0.05, compared to “OTI→WT” chimeras, ^§p < 0.05, compared to “MHCI^−/−OTI→WT” chimeras, by two-way ANOVA. Data represent results from two independent experiments.