Effect of danazol on NK cells and cytokines in the mouse uterus

Danazol, which has been used as a medicine for endometriosis, has a valid effect in pretreatment of patients receiving in vitro fertilization and embryo transfer, although its reproductive mechanism remains unclear. BALB/c mice were subcutaneously injected with danazol for 2 weeks. Blood and uteri were collected and cytokines were assayed. Following danazol treatment, an increase in pregnancy ratio was evident that was accompanied by up-regulation in serum macrophage-colony stimulating factor (M-CSF). RT-PCR analysis revealed that expression of M-CSF and Ly49, a phenotypic marker of natural killer (NK) cells, was up-regulated in the uteri of the danazol-treated mice. In immunohistochemical analysis, M-CSF and Ly49, together with alpha5 integrin, were clearly detected in the endometrium of the danazol-treated mice with very similar pattern of localization. These results suggest that danazol has an effect to promote pregnancy that induces recruitment of NK cells and a concomitant increase in the expression of M-CSF and alpha5 integrin in the uterus.