CD4 and endometriosis: CD4+/PD-1+ T cells were present more frequently among patients suffering from endometriosis stages I and II (9.01 ± 4.75%, median 9.01%, Min–Max 3.92–24.84%) and stages III and IV (12.36 ± 3.37%, median 11.33%, Min–Max 8.67–18.92%), than among patients from the control group (5.35 ± 1.54%, median 5.35%, Min–Max 2.65–7.69%) (Figure 2(a)).