Maternal lymphocyte responses during normal and abnormal pregnancies, measured in vitro using composite trophoblast antigens and phytohaemagglutinin

Evaluation of nonspecific immunity and plasma levels of interferon-gamma, interleukin-6 and tumor necrosis factor-alpha in preeclampsia

In this study we evaluated the maternal cell-mediated immune aspects of preeclampsia in terms of phagocytosis and killing of monocytes and polymorphonuclear cells. To evaluate the contribution of cytokines (Cks) in the pathophysiology of preeclampsia, we investigated the plasma levels of interferon-gamma (IFN-gamma), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha), respectively, by an enzyme-linked immunosorbent assay. Data showed that phagocytic and killing activities of monocytes were depressed in preeclamptic and normal pregnancies. At the same time, IFN-gamma plasma levels were undectable in both groups. Conversely, we detected significant levels of TNF-alpha in plasma from preeclamptic and normal pregnancies. Moreover, since in three preeclamptic patients the onset of severe preeclampsia was associated with a sharp increased of TNF-alpha plasma levels, we suggest that an increased production of this CK may be implicated in the pathophysiology of preeclampsia.

Cell-mediated immunity to trophoblast antigens in women with recurrent spontaneous abortion

OBJECTIVES

The purpose of this study was to determine whether trophoblast antigens activate cell-mediated immune responses in women with recurrent abortion of unknown cause by inducing lymphocyte proliferation and to correlate this with embryotoxic factor production.

STUDY DESIGN

Mononuclear cells were isolated from 57 nonpregnant women with recurrent abortion of unknown cause and from 10 fertile controls with normal reproductive histories. Lymphocyte proliferation assays were performed with trophoblast antigen extracts from the human choriocarcinoma cell lines Jeg-3 and JAR, fractionated trophoblast antigens, and for control, red blood cell membrane antigens. A stimulation index > 3 was considered significant stimulation. Trophoblast-stimulated culture supernatants were also tested for embryotoxic activity.

RESULTS

Thirty (52.6%) women with recurrent abortion of unknown cause responded to trophoblast antigen stimulation with a stimulation index > 3, whereas none of the control group responded. Neither patients with recurrent abortion nor women with normal reproductive histories responded to red blood cell membrane antigen. The mean stimulation index in the trophoblast antigen lymphocyte proliferation assay was significantly higher in women with recurrent abortion than in women with normal reproductive histories (3.99 +/- 2.82 vs 1.64 +/- 0.34, p < 0.01). Antigen extracts from the cytosol and membrane fractions of Jeg-3 provided the strongest stimulation. Lymphocyte proliferation correlated with embryotoxic factor production; 90.0% of women with a stimulation index > 3 and none of the controls produced embryotoxic factors after stimulation with trophoblast antigens.

CONCLUSION

In this study 52.6% of women with recurrent abortion of unknown cause compared with none in controls exhibited in vitro evidence of T-cell immunity to trophoblast antigen stimulation. Further work is needed to determine whether T-cell immunity to trophoblast is involved in the pathogenesis of recurrent spontaneous abortion.

Production of immunoreactive chorionic gonadotropin during mixed lymphocyte reactions: a possible selective mechanism for genetic diversity

Maternal immunologic recognition of the blastocyst as well as the hormone chorionic gonadotropin (CG) has been shown to be a requirement for successful implantation of the blastocyst and maintenance of the fetal graft. On the basis of these observations, we tested whether lymphocytes could produce chorionic gonadotropic-like hormones during a mixed lymphocyte reaction (MLR). Here we described the production of immunoreactive chorionic gonadotropin (ir-CG) as a result of an allogeneic stimulus but not other mitogenic stimuli. The kinetics of production, as monitored by immunofluorescence with antibody specific to the beta chain of the human CG (hCG) molecule, paralleled the blastogenic response. Gel filtration of the de novo-synthesized ir-CG showed the molecular weight of the intact molecule to be approximately 58,000. This molecule bound to a concanavalin A affinity column and also dissociated into two subunits of approximate molecular weights 32,000 and 18,000. These molecular weights are consistent with reported molecular weights for glycosylated intact hCG, as well as the beta and alpha chains of hCG, respectively. The material from the MLR but not the control cultures elicited significant testosterone production from Leydig cells, and this activity could be blocked by antiserum to hCG. The results described here, together with the fact that the blastocyst is implanted in a lymphocyte infiltrate, lend support to our postulate that lymphocyte-derived CG enhances successful implantation of the allogeneic fetus, thus providing a mechanism for selection of genetic diversity.