CD4 and Alzheimer disease: A significantly decreased percentage of B lymphocytes (-1.511 [-2.775, -0.248], <i>P</i> = 0.019) and CD8<sup>+</sup> T cells (-0.760 [-1.460, -0.061], <i>P</i> = 0.033) and a significantly increased CD4/CD8 ratio (0.615 [0.074, 1.156], <i>P</i> = 0.026) were observed in AD patients compared to HCs.