The interleukin-2 receptor on cord blood and nulliparous mononuclear cells is downregulated by maternal and cord blood serum.

The concentration of interleukin-2 receptor (IL-2R) on maternal, cord blood and unrelated nulliparous mononuclear cells has been studied after a previous phytohaemagglutinin (PHA) stimulation. Furthermore, the inhibitive action of maternal and cord blood serum on the IL-2R expression of stimulated nulliparous and cord blood lymphocytes has been shown. A downregulation of the [3H]-thymidine uptake by these PHA treated cells previously incubated in maternal and cord blood serum has been observed. Retroplacental serum was the most inhibitive experimental medium. The IL-2R modulation property of maternal serum has been studied during the pregnancy. Appearing quite early (in the sixth week), the maternal serum dependent inhibitive factor vanished, 2 to 3 weeks after delivery. After a study of the different serum components, it is suggested that the IL-2R downregulating molecule is included in the maternal immunoglobulin (IgG) fraction. Further experiments suggest that the addition of recombinant IL-2 during the action of low doses of maternal IgG allows a partial re-expression of the IL-2R. However, at physiological concentrations of IgG, the IL-2R downregulation becomes irreversible.

Modulation of the interleukin 2 receptor by maternal and cord blood serum.

In this report, the potential inhibitive action, of maternal serum (retroplacental and peripheral), and cord blood serum on the expression of the Il2r has been studied. Calf and male serum were used as a control. In order to have an optimal Il2r expression, a previous PHA cellular stimulation was performed. The maternal serum's Il2r inhibitive property was measured during and after the pregnant period. The presence of Il2r on maternal lymphocytes, cord blood cells, and unrelated donor mononuclear cells has been investigated (after a PHA stimulation assay). The downregulated Il2r expression of neoplastic cell line (Hut78 cell line) under the influence of maternal serum has been observed. The examination of the inhibitive action due to maternal serum has suggested that a factor included in the IgG fraction is mainly responsible for the downregulating property concerning the Il2r expression. A possible mechanism for the action of this factor has been studied. Further experiments suggest that the addition of recombinant Il2 during the action of low doses of maternal IgG allows a partial reexpression of the Il2 receptor. However, at physiological concentrations of IgG, the Interleukin 2 receptor downregulation becomes irreversible.

Functional modifications of the CD4+ and the CD8+ subset due to maternal serum.

Numerous experiments have been performed to try to explain the successful gestation of the semiallogeneic mammalian fetus in the immuno-competent mother. A popular hypothesis is that localized intra uterine suppression mediates the immune response and contributes directly to the survival of the fetus. Suppressive factors synthesized at the fetomaternal interface may be transported by the bloodstream and be found in the retroplacental and peripheral blood circulation. In this report we aim to study these modulating factors by exposing a proteinaceous antigen (Candidine or human mono nuclear cells) to unrelated human lymphocytes in the presence of a pool of maternal serum, retroplacental (MAT SR) or peripheral (MAT SP), or to a pool of male or calf serum (MALS or CS). A significant downregulation of the candidine mediated lymphocytic stimulation was observed in the case of the maternal serum. In order to further characterize this inhibition, a quantitative evaluation of the expression of the CD4 and CD8 positive subpopulations was performed. A selective inhibition of the CD4 positive subset was observed. In the PHA stimulation assay in the presence of maternal serum there was an inhibition of the thymidine uptake of unrelated lymphocytes. When studying the different subsets which were stimulated in the presence of maternal serum and control media it was shown that the CD4 positive subpopulation remained unchanged while there was a slight inhibition of the CD8 positive subset in the first case (maternal serum treated). The same CD4 positive inhibitive property of maternal serum was observed when a neoplastic cell line (HUT cells) was used as target for candidine in a stimulation test. This CD4 inhibited expression remained constant as long as the maternal serum was renewed. Maternal lymphocytes however remained resistant to the inhibitive action of maternal serum and did not show any change in their CD4 and CD8 positive subpopulation. By investigating the different blood components, it was shown that the suppressive factor was included in the IgG fraction and synthesized at the placental level. Appearing quite early during the gestation (at the 5-6th week), this factor was vanishing 2 weeks after the delivery.