[Prolonged survival of skin allografts in rats by injection of serum or a serum fraction extracted from pregnant rats]. / Survie prolongée d'allogreffes de peau chez le rat par injection de sérum ou d'une fraction sérique (IRG) extraite de rattes.

This work report the partial purification of an alpha 2-macroglobulin present in the serum of allopregnant rats. Ultrogel filtration followed by immune absorption on different antisera were used giving a single band on polyacrylamide gel electrophoresis. This fraction was able to inhibit in vitro T cell cytotoxic response to allogenic cells. When administered repeatedly to rats it significantly increased the survival of skin allograft. This alpha 2-macroglobulin fraction isolated from allopregnant rats was denominated IRG to its graft rejection inhibitory activity.

Rat pregnancy induces two suppressor cell activities.

Pregnancy in rat is able to stimulate two suppressor cell activities. One is specific to the paternal histocompatibility antigens and it resides in the T-lymphocyte population. The second is nonspecific and is of non-T nature. The use of various methods for pseudopregnancy and deciduoma installation has allowed the demonstration of two inducing circuits: (a) the presence of fertilized ova in the female genital tract and (b) the progestation hormonal status.

Rat pregnancy immunoregulatory circuits are progestation hormonal status, decidual tissue, embryo-trophoblast and late pregnancy changes dependent.

We have tested the spleen cells of rats for their reactivity to mating and unrelated (third party) strain alloantigens during pregnancy, pseudopregnancy, and traumatic deciduoma installation. By cytotoxic T-lymphocyte assays, after 7-day one-way mixed lymphocyte cultures (MLC), we detected the presence of many immunoregulatory circuits among rat pregnancy and postpartum. They are progestation hormonal status, decidual tissue, embryo-trophoblast, late-pregnancy-parturition-associated changes, and lactation-hormonal-status dependent.