Compared with breast cancer–free women, breast cancer survivors had decreased percentages of circulating eosinophils (−0.45% [95% CI, −0.87% to −0.03%]; P = .03), total CD4+ helper T cells (−1.50% [95% CI, −2.56% to −0.44%]; P = .01), and memory B cells (−0.22% [95% CI, −0.34% to −0.09%]; P = .001) and increased percentages of circulating naive B cells (0.46% [95% CI, 0.17%-0.75%]; P = .002). The gene discussed is CD4; the disease is breast carcinoma.