Detection of immunoglobulin A anticardiolipin antibodies in cervical mucus from in vitro fertilization patients and fertile women

Antiphospholipid antibodies in implantation failures

PROBLEM

The amino phospholipids (PL), phosphatidylserine (PS) and phosphatidylethanolamine (PE) are distributed asymmetrically in the plasma membranes of eucaryotic cells. This arrangement involves active transport of PS and PE from the outer to inner membrane leaflet by an aminophospholipid translocase (flipase). Cell activation, injury and programmed cell death (apoptosis) cause collapse of the PS/PE asymmetry by activation of another enzyme system, scramblase. Unlike other cells, the developing trophoblast exteriorizes PS during its differentiation.

METHODS OF STUDY

An analysis of published and unpublished data.

RESULTS

The trophoblast is targeted by antiphospholipid antibodies (aPL), especially to PS (aPS). Cardiolipin is not present in the trophoblast plasma membrane, nonetheless, anticardiolipin (aCL) has been implicated in trophoblast pathology. The aPS and aCL are often crossreactive. Both animal and in vitro experimental models have shown monoclonal and polyclonal aPS and aCL to specifically destroy trophoblast, inhibit syncytium formation, halt human chorionic gonadatropin (hCG) production, and limit trophoblast invasion. Antibodies to PE (aPE) have not been well characterized, however, recent reports from several independent laboratories document that aPE are associated significantly with very early (embryonic) recurrent pregnancy loss (RPL). Umeda and coworkers have shown that during cytokinesis (late telophase) of Chinese hamster ovary (CHO) cells, formation of PE rafts in cleavage furrows is required for completion of cell division and formation of daughter cells. This raises the question whether aPE might interfere with implantation and cell division during embryogenesis.

CONCLUSIONS

A role for aPL in implantation failure and occult pregnancy loss constitutes the basis of this overview.

Expression of antigens involved in the presentation of lipid antigens and induction of clonal anergy in the female reproductive tract

The molecular backgrounds of the anti-phospholipid syndrome and immunisation against the Rhesus proteolipid antigens are still largely unknown. In the present study, expression of (1) CD1, a major histocompatibility complex class l-like lipid antigen presenting molecule, (2) IL-10, a cytokine promoting induction of clonal anergy, and (3) CD80 and CD86, two T-cell costimulators preventing induction of clonal anergy when present, was investigated in frozen sections of cervix, corpus and the fallopian tube (FT) of 25-day-old BALB/c mice injected with FSH, progesterone or medium and of pregnant mice from each trimester (days 7, 14 and 19). CD1 was expressed by all endometrial epithelial cells. Enhanced immunostaining of the endometrial epithelial cells was observed after FSH treatment, and cervix and FT expressed generally more than the corpus of the uterus. After treatment with medroxy progesterone acetate (MPA), expression of CD1 by the endometrial epithelia was weak. During pregnancy CD1 was absent from the endometrium adjacent to the foetus, but was unaltered in the cervix and FT. IL-10 was expressed by the endometrial glands and also by the endometrial surface epithelium. MPA treatment increased the intensity of the IL-10 immunofluorescence. There were also chains of positive cells between the muscle bundles within the pregnant myometrium. CD80 and CD86 were usually absent from the female reproductive tract, but were occasionally found in the cervix during pregnancy. The present study demonstrates definite differences in the expression of both CD1 and IL-10 between the FSH and MPA treated mice, suggesting differences during the oestrous cycle. As IL-10 is expressed more in the secretory phase, it is probably involved in making the endometrium more acceptable for implantation by inducing clonal anergy. This is supported by the absence of CD80 and CD86. These results also suggest that abnormal expression of CD1d during pregnancy may predispose the mother for immunisation against lipid antigens such as membrane phospholipids and Rhesus-antigens.

Anti-phospholipid autoantibodies--do they have a pathogenic role in infertility?

Anti-phospholipid syndrome includes a variety of clinical manifestations, among which is recurrent pregnancy loss. Recently, it was suggested that anti-phospholipid antibodies might also have a role in infertility, mainly in unexplained infertility. Most of the studies report about an increased prevalence of these antibodies in infertile women; however, data regarding the implication of these antibodies on treatment outcome (mainly in in-vitro fertilization) and if there is a beneficial effect of treating these patients with aspirin, heparin and prednisone--remains still controversial. In this communication we review the literature reports of association of anti-phospholipid antibodies and infertility, and deal with the question whether they have a pathogenic role in these cases.