Suppression of natural killer cell activity by splenocyte transplantation in a rat model of endometriosis.

BACKGROUND One immune characteristic of endometriosis is a decrease in natural killer (NK) cell activity. This study was performed to determine whether an abnormal immune reaction in an endometriosis animal model could be transferred to an animal of the same species. METHODS An endometriosis model was prepared using 8 week old female rats by grafting a small section of one uterine horn onto the mesentery, followed 4 weeks later by removal of the spleen and remaining uterine horn. Splenocytes, that had been depleted of macrophages were injected via the tail vein, and NK cell activity of splenocytes was determined 4 days later. The uterus was simultaneously investigated immunohistochemically for immune cells. There was a control group (untreated; group 1), a control-splenocyte injection group (group 2), an experimental endometriosis model group (group 3) and an endometriosis model splenocyte injection group (group 4). RESULTS Splenocyte NK cell activity was decreased in group 3 to 42.0% of that of group 1 and in group 4 to 38.9%. Immunohistologically, the number of NK cells in groups 3 and 4 markedly decreased to 62.0 and 55.1% of group 1 respectively. CONCLUSION It was demonstrated that abnormal immunity caused by allograft of immune cells could recur in an endometriosis rat model.