CXCR4 and infection: Indeed, uterine-derived NK (uNK) cells (but not pbNK cells) activated in vitro with IL-12 and IL-15, inhibited infection of cell lines, PBMCs, and primary human endometrial cells with strains of HIV that use CXCR4 for cell entry.212 The inhibitory activity was associated with uNK-produced CXCL12, a CXCR4 ligand, and supressed by CXCL12 neutralising antibodies.212 Moreover, dNK cells significantly delayed and reduced infection of decidual macrophages with HIV strains that use CCR5 for entry.