Phenotypic analysis of circulating lymphocytes in post challenge mice. PBMCs were collected and purified from the blood of all mice in Figure 3 above that were challenged with B16.F10 melanoma cells. Cells from mice that were resistant to challenge and remained tumor-free (n = 20) or non-resistant to challenge that developed a secondary tumor (n = 35) were stained with antibodies for CD3, CD4, CD8, and memory markers CD62L and CD45RB. Dot plots (a) are representative of resistant and non-resistant mice. Each dot represents a cell gated on CD4+CD3+ or CD8+CD3+ parent populations. Cumulative data for the subpopulations are presented as mean percentage of the parent T cell population from resistant (■) and non-resistant (◻) mice (b). Error bars represent standard deviation. E, effector; N, naïve; CM, central memory; EM, effector memory. * P < 0.05, ** P < 0.01, *** P < 0.001.