The integrin subunits alpha 2, alpha 3, alpha 4, alpha 5, alpha 6, alpha V, beta 1 and beta 3 in fetal, infant and adult human spleen as detected by immunohistochemistry.

This immunohistochemical study describes the expression of the integrin receptor subunits beta 1, beta 3, alpha 2, alpha 3, alpha 4, alpha 5, alpha 6 and alpha V 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 beta 1, alpha 3, alpha 4, alpha 5 and alpha V subunits. In adults these cell types also slightly expressed the alpha 2 subunit, whereas fetal and infant spleens were negative. alpha 6 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 beta 3 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 beta 3 and alpha 6 subunits. In fetuses beta 1 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.(ABSTRACT TRUNCATED AT 250 WORDS)