Endometriosis: abnormal endometrium and dysfunctional immune response.

This review highlights recent studies that illuminate the role of the immune system in endometriosis. The findings are discussed in the framework of a model which proposes that endometriosis reflects an immunological selection process. Endometrial cells, which are inherently resistant to apoptosis and immune-mediated elimination, acquire the capacity to utilize the products of an activated immune system to establish ectopic foci of disease. Cyclical inflammatory/immune cell stimulation that fails to eliminate ectopic endometrial implants results in progressive immunological derangement and associated pathophysiological changes which are characteristic of the disease.