Neutrophil depletion reduces endometriotic lesion formation in mice

Problem Neutrophils are known to be accumulated in endometriosis; however, direct evidence of the impact of neutrophils in the development of endometriosis was lacking. To clarify the importance of neutrophils, we examined the effect of neutrophil depletion on the development of endometriosis. Method of study Ovariectomized, estradiol‐replaced, 8‐week‐old, female BALB /c mice were injected with endometrial fragments (Day 0). Neutrophils were depleted by anti‐Gr‐1 antibody, either in the early stage (from Day 1 to Day 3, group E) or late stage (from Day 8 to Day 12, group L). Control mice (group C) did not receive antibodies. On Day 14, mice were killed and the number and weight of endometriotic lesions were counted and weighed. Results The number of endometriotic lesions was significantly less in group E in comparison with Group C and Group L. Weight per lesion did not differ between groups. Conclusion Neutrophils are essential for the initial formation of endometriosis.