Spontaneous production of interleukin-1-like factors from pregnant rabbit uterine cervix

Uterine cervical explants in culture from pregnant rabbits at term spontaneously synthesized and secreted three species of interleukin-1-like factors in culture medium. The addition of the exogenous mitogen lipopolysaccharide to the culture system induced further release of these factors. However, these phenomena were not observed with explants from nonpregnant cervices. The molecular weights of these factors estimated by gel filtration were approximately 49, 22, and 12 kDa, respectively, and were identical to those of interleukin-1 from rabbit macrophages and polymorphonuclear leukocytes. These results indicate that interleukin-1-like factors are involved in cervical ripening and dilatation, especially in the acceleration of collagenase production, at term.