Effect of the intrauterine contraceptive device on protein components of human uterine fluid.

The albumin, immunoglobulin G (IgG), immunoglobulin A (IgA), lysozyme, lactoferrin, alpha 1-antitrypsin, alpha 1x-antichymotrypsin, and neutral proteinase levels of uterine fluid and serum of IUD-bearing women were studied in relationship to the phase of the menstrual cycle, the length of IUD implantation and the presence of reported side effects. Selection of these proteins was based on their potential importance in IUD-induced contraceptive action and/or side effects. Generally, only small differences were found in the serum levels of these proteins during the cycle, with different length of implantation or between patients with and without side effects. However, transudation of proteins (albumin, IgG, alpha 1-antitrypsin, alpha 1x-antichymotrypsin) from blood into the uterine cavity was enhanced by the IUD, especially during the postmenstrual and premenstrual periods. The IUD enhanced the local secretory response even more, i.e., the increased release of proteins from the endometrium (lysozyme, neutral proteinase, IgA) and from leukocytes (lysozyme, lactoferrin). Protein changes occurred as the period of insertion increased. These changes in the uterine milieu may account in part for the contraceptive action of the IUD. The secretory proteins rather than the transudation products differed between patients who showed IUD-associated side effects vs. those who did not, implying that IUD-related pathology is primarily associated with changes in local secretory response. The possible role of each protein in the mechanism of IUD action is presented in view of the present findings.