Objective: To evaluate the correlation between natural killer cell activity and serum estradiol (E2) levels in patients with different stages of endometriosis.
Methods: Natural killer cell activity of peripheral blood lymphocytes and serum E2 levels were evaluated in 73 women who underwent laparoscopy for pelvic pain, infertility, and benign adnexal masses.
Results: The 33 patients (45%) with endometriosis showed a significant decrease in natural killer cell activity in relationship to an increase in disease stage (correlation coefficient r = -0.83, P < .001). A significant inverse relationship was observed between cytotoxicity and serum E2 levels (correlation coefficient r = -0.89, P < .001).
Conclusion: The relationship between natural killer cell activity and serum E2 levels suggests that an immunoendocrine interaction plays an important role in the progression of endometriosis.