Rheumatoid Factor-Associated High-Molecular-Weight Complexes in the Menstrual and Amniotic Fluids

Abstract

We have previously described the identification of the human decidua-associated protein hDP200 as a rheumatoid factor [1], Assuming that rheumatoid factor binds to Fc of immunoglobulins, the existence of high-molecular-weight complexes was studie in decidual extract, pooled uterine fluid from proliferative and early secretory phase, menstrual fluid and amniotic fluid. High-molecular-weight complexes containing hDP200 and other immunoglobulins were found only in menstrual and amniotic fluids and not in decidual extract or uterine fluid. It is possible that complexing of the immunoglobulins by hDP200 serves as one of the mechanisms that ensure suppression of the immune response to fetal antigens.

Placental Levels of Human Decidua- Associated Protein 200 in Normal Pregnancy and Missed Abortion

“…Furthermore, no significant difference in the intrauterine level of hDP200 and the pattern of its decrease was observed comparing normal pregnancy and missed abortion [8]. This observation, in addition to the previous finding of high-molecular-weight complexes composed of hDP200 associated with immunoglobulins in amniotic fluid [7], prompted us to examine the existence of hDP200 in extracts of placental tissue in normal pregnancy and missed abortion.…”

“…It might be that there is a steady state of hDP200 (rheumatoid factor) synthesis and immune complex formation in placenta, while there is less secretion of this rheumatoid factor into amniotic fluid or there are less antibodies available for immune complex formation in amniotic fluid in the second trimester. It seems logical to find such antibodies available more in the area of the feto-maternal interface, and since our double-site ELISA detects the complexed form of hDP200, also containing other immunoglobulins besides rheumatoid factor [7], it is not surprising to find higher levels of hDP200 in placenta than in amniotic fluid throughout pregnancy. It is possible that this monoclonal rheumatoid factor might be required for a kind of immunological process, such as suppression of the immune response against paternal antigens, by neutralizing the antibodies available in the area of feto-maternal interface.…”

“…This immunoglobulin, being a secretory glycoprotein [2], was found in uterine luminal fluid [3][4][5], menstrual fluid [6,7] and amniotic fluid [7,8]. Whereas the role of hDP200 has not yet been determined, previous studies demonstrated consistent fluctuations in its concentration throughout the menstrual cycle [3], as well as a consistent decrease in its amniotic fluid level, as observed between 9 and 20 weeks of pregnancy [8].…”

Intrauterine Levels of Human Decidua-Associated Protein (hDP) 200 in Normal Pregnancy and Missed Abortion

“…The other point being that endometrial proteins mentioned above, as opposed to hDP 200, are detected in maternal serum in quite high levels, and therefore, the level of these proteins in amniotic fluid samples obtained transcervically after dilatation of the cervix might be affected by blood contamination. On the contrary, hDP 200, found locally in the uterus, is not detected in maternal serum [4] and, therefore, there is no effect of blood contamination on amniotic fluid levels of hDP 200. Furthermore, the issue of hDP 200 and hemoglobin concentration in menstrual fluid samples was examined, and no correlation was found, thus demonstrating that the vascular system is not the source of the hDP 200 [5].…”

“…This immunoglobulin, being a secretory glycoprotein [1], was found in uterine luminal fluid, demonstrating consistent fluctuations in its concentration throughout the menstrual cycle [3]. Furthermore, the existence of high-molecular-weight complexes, composed of hDP 200 associated with immunoglobulins, was demonstrated in uterine lumen [2,4]. Whereas the role of this protein has not been determined yet, previous studies demonstrated that it may be involved in the implantation process [5,6].…”