CD8A and cholesteryl ester measurement: To evaluate whether the levels of endometrial immune cells were modulated by PRP treatment, the CD56+ NK cells, CD8+ T cells, CD68+ macrophage cells, CD163+ macrophage cells, Foxp3+ Treg cells, T-bet+ Th1 cells, and GATA3+ Th2 cells were examined with the use of IHC staining in persistent CE patients before and after PRP treatment (Figure 3A).