Intraperitoneal and subcutaneous treatment of experimental endometriosis with recombinant human interferon-alpha-2b in a murine model.

OBJECTIVE: To determine the effect of human interferon (IFN)-alpha-2b on experimental endometriosis in rats.
DESIGN: Experimental, controlled, double-blind randomized study.
SETTING: Experimental surgery laboratory in a university department. ANIMAL(S): Ninety-six Wistar rats with endometriosis, induced by transplanting four endometrial fragments into the peritoneal cavity. INTERVENTION(S): One third of the animals served as controls (group A). The others were randomly divided into two groups and were given IFN-alpha-2b either as a single intraperitoneal dose (group B) or as three SC doses (on alternate days) (group C). MAIN OUTCOME MEASURE(S): Laparotomy was performed to measure the size of each implant at various times (days 0, 6, 12, 20, and 120 after treatment). RESULT(S): There were no differences among the groups in the size of the average implants before IFN was administered (17.3+/-6.7, 19.7+/-7.8, and 18.1+/-9.2 mm for groups A, B, and C, respectively). These values were significantly smaller after treatment in group B (14.9+/-8.0 mm) and group C (14.0+/-9.5 mm) than in the control group (17.6+/-7.5 mm) (P<.05). Intraperitoneal IFN produced an initial maximum decrease in the size of the implants (40% reduction on day 6), which diminished until day 20 (20%) and then was maintained on a plateau until day 120 (25%). By contrast, group C showed an initial minimal reduction (13% at day 6), which increased up to day 20 (19%), after which a plateau was reached (23% at day 120). Thus, the effects in both treatment groups were similar in the long term. CONCLUSION(S): Two short regimens of human IFN-alpha-2b reduced the size of experimental endometriosis in rats.