Moreover, we analyzed the relationship between the key genes and immune cells, and found that CXCR6, GZMK, and KLRG1 were positively correlated with T cells CD8, and negatively correlated with T cells CD4 naïve and monocytes in both OA and MDD (Figure 5C,D). The gene discussed is CXCR6; the disease is major depressive disorder.