Compared with those in the healthy endometrium tissue samples to Endometriosis samples, the infiltration B cells memory, CD8+ T cells, resting CD4+ T cells memory, activated CD4+ T cells memory, T cells gamma delta, monocytes, M1 macrophages, M2 macrophages, and resting mast cells were significantly upregulated and the infiltration levels of plasma cells, Tregs, resting NK cells, activated NK cells, and activated dendritic cells downregulated in the EMs samples. The gene discussed is CD8A; the disease is endometriosis.