[Study on the changes of T-lymphocyte subsets in the patients with endometriosis]

To investigate the function of T-lymphocyte subsets in patients with endometriosis.

The levels of interleukin-2 (IL-2) and interleukin-6 (IL-6) in the serum, and peritoneal fluid of 30 cases with endometriosis were detected using enzyme linked immunoabsorbent assay and compared with those of 20 non-endometriosis cases. The expression of IL-2 and IL-6 in ectopic endometrial tissue from the patients with endometriosis and the endometrial tissues of 10 normal women was investigated by immunohistochemistry method.

Significantly elevated levels of IL-6 (cytokines of T help cell 2) were found in the serum and peritoneal fluid of patients with endometriosis (Median: 5.3 ng/L, 2.1 ng/L, P < 0.05) compared with that of non-endometriosis patients median: 2.5 ng/L, 0.9 ng/L). The level of IL-6 in the serum and peritoneal fluid of endometriosis patients in early stages (stages I, II) was 3.7 ng/L, 1.6 ng/L, significantly lower than those in advanced stages (stages III, IV) (13.6 ng/L, 4.1 ng/L) (P < 0.05). The ratio of IL-2/IL-6 in the serum and peritoneal fluid in patients with endometriosis (0.7, 1.1) was significantly lower than those in the control non-endometriosis group (0.8, 6.2, P < 0.05). The levels of IL-6 detected in the peritoneal fluid of patients with endometriosis had a positive correlation with those in the serum (r = 0.745, P < 0.01). The levels of IL-6 in serum and peritoneal fluid in the patients with endometriosis had a negative correlation with the IL-2/IL-6 ratios in the serum and peritoneal fluid respectively (r = -0.406, r = -0.480, P < 0.05). IL-2 and IL-6 were expressed in the interstitial cells of ectopic endometrial tissue, with an expression rate of 56.7%, and 60.0% respectively. There was significant difference in the expression of IL-2 and IL-6 between the ectopic endometrial tissue and normal endometrial tissue.

The levels of IL-6 in the serum and peritoneal fluid of patients with endometriosis are increased, implying that IL-6 might play a role in the pathophysiology of endometriosis. The ratio of IL-2/IL-6 in the serum and peritoneal fluid was decreased in patients with endometriosis compared with the control group, suggesting shift of Th1 cell toward Th2 cell in patients with endometriosis. Stronger expression of IL-2 and IL-6 in the ectopic endometrial tissues may contribute to the disturbed immune regulation in patients with endometriosis.