CD4 and nonpapillary renal cell carcinoma: Representative examples of the flow cytometry histograms (Fig. 3b) illustrate that in some of the ICI-treated animals but not in any of the control animals, CD4+ and CD8+ T cells displayed activation upon exposure to ccRCC cell lines to an extent that is similar to activation observed with α-CD3/α-CD28 beads in the absence of co-culture.