Objective: Our purpose was to test the hypothesis that menstruation and intrapelvic injection of endometrium for the induction of endometriosis affect inflammatory parameters in peritoneal fluid from baboons.
Study design: In the first part of this study, 107 laparoscopies were performed in 62 female baboons with a normal pelvis during menstruation, the follicular phase, and the luteal phase. In the second part of this study, 21 baboons were studied during paired laparoscopies in the follicular phase and the luteal phase of the cycle. In the third part of this study, 11 baboons were studied by paired laparoscopies during menses and during the nonmenstrual phase of the cycle. In the fourth part of this study, paired laparoscopies were performed in 7 baboons before and after intrapelvic injection of endometrium. Peritoneal fluid was aspirated and measured in all laparoscopies and assessed for leukocyte concentration. In the third and fourth parts of the study, peritoneal fluid was analyzed for the concentrations of inflammatory cytokines and for the proportions of cells with immunohistochemical staining positive for these cytokines.
Results: During menstruation, in comparison with nonmenstrual phases of the cycle, the leukocyte concentration of the peritoneal fluid was increased significantly, as were the proportions of peritoneal fluid cells with positive staining for tumor necrosis factor alpha, transforming growth factor beta(1), and intercellular adhesion molecule 1 and the peritoneal fluid concentrations of transforming growth factor beta(1) and interleukin 6. After intrapelvic injection of endometrium, the peritoneal fluid leukocyte concentration and the proportions of peritoneal fluid cells with positive staining for tumor necrosis factor alpha, transforming growth factor beta(1), CD3, and human leukocyte antigen (DR locus) significantly increased.
Conclusion: Subclinical peritoneal inflammation occurs in baboons during menstruation and after intrapelvic injection of endometrium.