The frequencies of CD19+/PD-1+ B cells were also higher in patients with endometriosis stages I and II (4.07 ± 2.59%, median 3.95%, Min–Max 0.9–10.82%) and stages III and IV (4.56 ± 3.63%, median 3.23%, Min–Max 0.54–11.37%) than in those of healthy subjects (1.67 ± 0.84%, median 1.81%, Min–Max 0.37–3.01%) (Figure 2(c)). Here, CD19 is linked to endometriosis.