Localization and quantitation of a low molecular weight proteinase inhibitor, antileukoprotease, in the human uterus.

Antileukoprotease was demonstrated in the cervical mucosa, but was absent in the endometrium. It was shown immunohistologically to predominate in the epithelial lining of the cervical crypts. High concentrations were found in the cervical mucus. Although antileukoprotease was not present in the endometrium, low concentrations were found in the uterine fluid, probably secondary to diffusion from the cervical mucus. The concentration of antileukoprotease in cervical mucus varied greatly during the menstrual cycle, but no midcycle minimum was found. Increased concentrations were found in samples obtained during the week preceding onset of the menstruation in most women. Antileukoprotease was present in uterine fluid from intra uterine device (IUD) non-users in its free form. In fluid from IUD users it was partly in its free form, and partly in a complexed form. The major part of the non-complexed portion was biologically active. The complex consisted, at least partly, of elastase bound to antileukoprotease. Antileukoprotease may thus contribute to the neutralization of granulocyte elastase in the uterine fluid of IUD users.