Fig 1: Representative flow cytometric analysis of CD62L and CD44 expression in CD4+ (A) or CD8+ (B) T cells from peripheral blood of mice (N = 5) xenografted with the KO#7 clone compared with age matched naïve mice at the time of sacrifice shows an increase in activated effector T-cells (CD44intCD62Llo) and memory T-cells (CD44hiCD62Llo) only in the mice xenografted with KO#7 cells (A and B). Following in vitro activation using the BioLegend cell activator cocktail (N = 3), there is a significant increase in levels of the Ifn-? and Tnf-a cytokines in CD4+ cells from the spleens compared with untreated, age-matched naive control mice (C and D). Tumor killing assays (N = 3) in vitro demonstrate proportionally increased annexin V+ staining in BBC2 KO#7 cells when cultured with increasing levels of CD8+ cells derived from KO#7 xenografted mice (E and F) but not when co-cultured with CD8+ cells from naive mice. In addition, the inclusion of CD4+ T helper cells leads to increasesd annexin V+ staining in BBC2 KO#7 cells (E and F). These tumor-killing CD8+ cells derived from mice engrafted with KO#7 cells, compared with cells from wild type mice, also showed increased levels of Ifng and TnfA cytokines (G and H). ns = not significant, * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001