Endocrinology, Vol 119, 2427-2432, Copyright © 1986 by Endocrine Society

ARTICLES

Immunoglobulin and secretory component regulation in the rat uterus at the time of decidualization

JE Stern and CR Wira

To determine the effect of decidualization on uterine immunoglobulins (Igs), we measured the levels of IgG, IgA, and secretory component (SC) after induction of artificial decidual cell reactions (DCR) in hormonally primed ovariectomized rats. When progesterone-treated (2.5 mg/day, 3 days) rats received an intraluminal instillation of oil or a needle scratch stimulation in one uterine horn, the stimulated horn had an increase in wet weight and cytoplasmic protein relative to the contralateral horn. Under these conditions, IgG levels increased 10- fold in the lumen of the stimulated horn. This response was selective for IgG, because induction of DCR had no effect on accumulation of IgA or SC in the stimulated horn. The progesterone-induced accumulation of IgG after DCR was further enhanced by estradiol. The addition of a small amount of estradiol (0.2 microgram) on day 3 of a 4-day progesterone pretreatment resulted in further increases in both the wet weight of the stimulated horn and the concentration of IgG in the lumen. The amount of IgG in the lumen of the stimulated horn was 5-fold greater than that in the stimulated horn after progesterone alone. Levels of IgA and SC, however, remained unchanged with this treatment. These results indicate that movement of IgG into the uterine lumen occurs as a part of the DCR and that both an appropriate endocrine balance and physical stimulation are essential for maximal IgG accumulation. Further, they suggest that IgG may play a central role in early pregnancy, which results in the successful implantation of the blastocysts.