Inhibitors of trypsin, chymotrypsin and elastase in human uterine fluid.

Pure uterine fluid, obtained from 18 women in the luteal phase, was pooled and gel filtered. Inhibitory activity against trypsin, chymotrypsin and elastase was present in fractions containing alpha 2-macroglobulin, alpha 1-antitrypsin, alpha 1-antichymotrypsin and antileukoprotease. After solid-phase adsorption with antibodies to these inhibitors, no inhibitory activity remained. It was concluded that the entire inhibitory capacity of the proteinases studied was attributable to inhibitors derived from serum and antileukoprotease. These proteinase inhibitors which are present in uterine fluid during the luteal phase might be of significance during the implantation process.