Abstract
Abstract This immunohistochemical study describes the expression of the integrin receptor subunits β1, β3, α2, α3, α4, α5, α6 and αV in cells of the splenic red and white pulp in 34 human spleens (23 fetuses of 16–24 gestational weeks (GW), two infants and nine adults). The distribution of the integrin subunits is compared with that of the extracellular matrix (ECM) proteins types IV and III collagen, laminin, fibronectin, tenascin and vitronectin, known to be present in reticular fibers of the spleen. In the red pulp of developing and adult spleen, reticular cells, endothelial cells, myofibroblasts and macrophages expressed β1, α3, α4, α5 and αV subunits. In adults these cell types also slightly expressed the α2 subunit, whereas fetal and infant spleens were negative. α6 subunit was strongly expressed in endothelial cells and moderately in platelets and macrophages of adult spleens. Reticular cells of fetuses aged 16–19 GW expressed β3 subunit, whereas in older fetuses, infants and adults it was not possible to distinguish them with certainty from the strongly positive platelets and macrophages. The expression of the subunits corresponded well with the distribution of their ECM protein ligands. In the white pulp lymphocytes did not express β3 and α6 subunits. In fetuses β1 was expressed only on some lymphocytes of the white pulp, and in adults on some lymphocytes of periarterial lymphatic sheath and marginal zone, where the corresponding ligands are also located. Contrary to the scarcity of β subunits, α3, α4, α5 and αV subunits were expressed on all lymphocytes of fetal and adult white pulp. α2 subunit was slightly expressed only on lymphocytes of adult white pulp. These findings suggest a possibility that β subunits other than β1 and β3 form the components of the integrin receptors of most lymphocytes in the white pulp of fetal and adult human spleens.
Published Version
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