While there are likely to be many factors in the development of endometriosis, evidence compiled at the University of Kansas Medical Center in Kansas City shows that women with endometriosis often have high levels of cytokines - proteins released during an immune response. In particular, they found that the cytokine tumour necrosis factor (TNF)-alpha was very common in women with endometriosis.

The research is still in its infancy, but the researchers note that disturbed levels of other cytokines, cell apoptosis, and T- and B-cell abnormalities are also common, all consistent with an autoimmune disease (Fertil Steril, 2001; 76: 223-31).