CD4 and breast cancer: Furthermore, when we compared BC patients before chemotherapy with HD, we found: (a) a decrease in the naive CD8+ T cell population (Pop3), (b) an increase in two central memory CD8+ T cell populations expressing exhaustion markers (Pop5 and Pop10), (c) an increase in two CM (Pop14 and Pop19) and one EM (Pop18) populations in the CD4 T cell compartment that expressed exhaustion markers, particularly TIM3, (d) an increase of CD4 T CM population with a senescent phenotype (Pop21), and (e) a decrease in naive and CM (Pop20 and Pop22, respectively; Fig 4D).