Characterization of one alpha 2-macroglobulin with anticomplementary activity from pregnant women.

In 15 pregnant women during the third term of pregnancy, the immunomodulatory property of alpha 2-macroglobulin (alpha 2M) was initially detected by measuring the inhibitory effect on immune complement-dependent haemolysis of serum alpha 2M fractions obtained by gel filtration. By a two-step chromatography procedure consisting of gel filtration followed by anion-exchange chromatography, different sub-forms of alpha 2M in serum were separated. Amongst them, it was shown that the inhibition of complement activity was almost exclusively linked to one particular subform. Additional studies revealed that the observed effect was not due to proteases bound to alpha 2M during clotting since, by using protease-specific inhibitors, no change was observed in complement inhibition. This subform, though present at very low levels in control sera, appeared in strikingly increased amounts during the third trimester of pregnancy (35 mg/l) and comprised between 3 and 5% of the total alpha 2M. Results show that the increase of alpha 2M anticomplementary activity is linked to the increase in alpha 2M levels in serum.

[Inhibition of an immune hemolysis reaction in higher vertebrates by a serum fraction (fraction P) from the pregnant Salamandra salamandra L]. / Inhibition d'une réaction d'hémolyse immune chez les vertébrés supérieurs par une fraction sérique (fraction P) de femelle gestante chez Salamandra salamandra L.

Serum "fraction P" from Salamandra pregnant female (containing essentially an alpha 2-macroglobulin) possesses non specific cellular immunosuppressive properties [2]. This fraction has been tested in an immune hemolysis reaction: hemolytic Rabbit IgG + guinea-pig complement + Sheep erythrocytes. This fraction, after incubation with guinea-pig complement, inhibits immune lysis.

[Separation and study of two serum factors involved in the inhibition of the maternal cytotoxic reaction against embryonic cells in pregnant salamandra (author's transl)]. / Séparation et étude de deux facteurs sériques responsables de l'inhibition de la réaction cytotoxique maternelle à l'égard des cellules embryonnaires, chez la salamandre gestante.

In vitro experiments in pregnant salamanders show a maternal specific cytotoxic reaction against larvae cells and an inhibition of this reaction by maternal serum. The last one is double: non-specific inhibition of maternal cellular reaction and specific protection of embryonic cells. Two fractions have been isolated from maternal serum, with biological properties in cell cultures: the first one is a protein (migrating as alpha2-macroglobulin does) which is implied in non-specific immunosuppression of maternal cells; the second fraction contains an IgM and specifically protects embryonic cells against maternal cytotoxicity.