KIR2DL1 and endometriosis: Research into NK cell stimulating therapies for endometriosis can be divided into four categories: (1) blocking of inhibitory receptors such as KIR2DL1, LILRB1/2, NKG2A and PD-1/PD-L1; (2) inhibiting cytokines such as TGF-β; (3) stimulating NK cell with IL-2, and (4) mycobacterial treatment with BCG.