Finally, the frequencies of CD19+/PD-L1+ B cells were higher in patients with stage I and II endometriosis (3.85 ± 3.08%, median 3.08%, Min–Max 0.13–9.51%) and in patients with more advanced stage III and IV endometriosis (4.57 ± 3.88%, median 2.97%, Min–Max 1.05–10.98%) than in patients from the control group (0.26 ± 0.23%, median 0.20%, Min–Max 0.07–1.03%) (Figure 2(f)). Here, CD19 is linked to endometriosis.