Expression of mucosal addressin cell adhesion molecule-1 on the reticular framework between white pulp and the marginal zone in the human spleen.

The antigenic heterogeneity of the reticular framework of the white pulp and marginal zone is well documented in the human adult spleen. Immunostaining of α-smooth muscle actin characterizes the heterogeneity of the reticular framework of the white pulp and marginal zone. In the human spleen, the blood cells flow in an open circulation. T and B lymphocytes flow out from the arterial terminal, and migrate in the reticular framework. Homing of lymphocytes to lymphoid tissues is regulated by selective interactions between cell surface homing receptors and tissue vascular addressins at sites of lymphocyte recruitment from the blood. In the present study, mucosal addressin cell adhesion molecule-1 was selectively expressed on α-smooth muscle actin-positive reticular framework. The reticular framework may function in lymphocyte homing and segregation into the periarteriolar lymphoid sheath, lymph follicle and marginal zone.