CD4 and major depressive disorder: The present study revealed that patients with combined anxiety and depression, isolated anxiety, isolated depression, and neither condition showed significantly higher levels of CD3, CD4, CD8, NK cells, and CD4/CD8, and lower NLR compared to other groups, with statistical significance (P = 0.044, P = 0.001, P = 0.022, P = 0.039, P = 0.007, and P = 0.003).