Fig. 5. The Fbxl19-encoded DA9 peptide is presented by ERAAP-KO cells to WT CD8 T cells.

WT B6 mice were immunized with ERAAP-KO spleen cells, and immune responses to the DA9 and FL9 peptides were measured directly ex vivo by intracellular IFNγ staining. Forward and side scatter were used to exclude dead and granular cells, and the cells in the resulting lymphocyte gate were B220-CD4-CD8α+TCRβ+. A. Representative flow cytometry plots show CD8 T cells from immunized, but not naïve mice downregulate L-selectin (CD62L) and produce IFNγ when restimulated with either the DA9 or FL9 synthetic peptides. B. Fraction of CD62L^lo IFNγ⁺ cells in naive wild-type mice (open) or immunized with ERAAP-KO cells (closed). Each point represents an individual animal. Results from eight mice, from two pooled experiments are shown, with the bars representing standard error of the mean. When analyzed by non-parametric one way ANOVA (Kruskal-Wallis with Dunn’s post-test), the data are statistically significant, with p=0006.