Distribution of cell adhesion molecules in decidua of early human pregnancy. An immunohistochemical study.

Background: The aim of the study was to investigate human decidua for cell adhesion molecules involved in interactions between the various different maternal and fetal cell populations, homing of the unusual intradecidual population of CD56+ lymphocytes, and organization of the decidual extracellular matrix.

Experimental Design: First trimester human decidua from normal pregnancies was investigated immunohistochemically with antibodies against integrin subunits (alpha 1-6, alpha L, alpha M, alpha X, alpha IIb, alpha V, beta 1, beta 3, and beta 4), platelet-endothelial cell adhesion molecule, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and L-selectin.

Results: Endometrial glands stained for alpha 1, alpha 2, alpha 3, alpha 5, alpha 6, alpha V, beta 1, beta 3, and beta 4, and stromal cells for alpha 1, alpha 3, alpha 5, alpha 6, alpha V, beta 1, beta 3, ICAM-1, and VCAM-1. Endothelium stained for alpha 1, alpha 2, alpha 3, alpha 4, alpha 5, alpha 6, alpha V, alpha IIb, beta 1, beta 3, and beta 4; platelet-endothelial cell adhesion molecule and ICAM-1 also were found on the endothelium of a large number of blood vessels of all types, and VCAM-1 on the endothelium of a moderate number of arterioles and venules, and a few capillaries. Weak staining for E-selectin was seen in a moderate number of arterioles and venules. Large numbers of lymphocytes stained for alpha 4, alpha L, alpha M, alpha X, beta 1, and moderate or small numbers for alpha 1, alpha 3, alpha 5, alpha v, beta 3, platelet-endothelial cell adhesion molecule, ICAM-1, and L-selectin.

Conclusions: Decidual stromal cells, like endometrial glands and endothelium, express integrins that bind basement membrane components. These integrins represent the basis for the formation of the pericellular basement membrane of these cells. They also bind certain glycoproteins that support outgrowth and attachment of the trophoblast in vitro. Vitronectin-binding integrins on endometrial glands, stromal cells, and endothelium may be involved in adhesion of the trophoblast through vitronectin on its surface. From our findings and published data it seems that adhesion of alpha 1 beta 2 (leukocyte function-associated antigen-1) on lymphocytes to ICAM-1 on the endothelium plays the most important role in the migration of CD56+ lymphocytes from the peripheral blood into the decidua. The expression of several beta 1 (VLA) integrins on lymphocytes suggests that these cells are activated, and, like the expression of ICAM-1 and VCAM-1 on stromal cells, probably contributes to their retention in the decidual stroma.