Peritoneal fluid concentrations of interleukin-4 in relation to the presence of endometriosis, its stage and the phase of the menstrual cycle

Background Interleukin-d, (IL-4) is a cytokine with both stimulatory and in hibitory effects on the inflammatory system such as macrophage inhibition a nd T-cell activation. It is known to regulate several monocyte functions, i ncluding inhibition of the synthesis of cytokines such as IL-1, IL-6 and TN F-alpha as well as potentiating IL-8. Method In an attempt to clarify the association between IL-4 and endometrio sis, we measured the concentration of IL-4 in the peritoneal fluid of 52 wo men; 24 with endometriosis and 28 with no endometriosis, controlling for th e phase of the cycle and the stage of disease. Results. There was no difference in the concentrations of IL-4 between wome n with (n=28) and without endometriosis (n=24). No difference was found bet ween the IL-4 concentrations in women with different stages of endometriosi s. Levels of IL-4 did not show a difference according to the phase of the c ycle in tither group. Conclusion. Our results indicate no association between peritoneal fluid le vels of IL-4 and endometriosis and hence suggest that IL-4 is not involved in the pathogenesis of endometriosis.