CD4 and Alzheimer disease: The results revealed a higher frequency of CD3+ (15.5 ± 4.51 per 1 mm2) and CD4+ (11.57 ± 4.32 per 1 mm2) cells in the AD group compared to the control group (CD3+, 0.64 ± 0.89; CD4+, 0.5 ± 0.3 per 1 mm2) and the PPE + AD group (CD3+, 6.28 ± 3.49; CD4+, 4.46 ± 1.83 per 1 mm2), respectively.