CD4 and nonpapillary renal cell carcinoma: However, PBRM1MUT ccRCC tissues showed lower proportions of CD8+ T cells (P=0.004) and activated CD4+ memory T cells (P=0.403), and significantly higher proportion of resting mast cells (P<0.001) compared to the PBRM1WT ccRCC tissues (Figure 2B), and other immune cell types in the ccRCC TME exhibited weak correlation with the PBRM1MUT genotype.