Immunohistochemical characterization of rat thymic non-lymphoid cells. I. Epithelial and mesenchymal components defined by monoclonal antibodies.

Molecular microenvironmental heterogeneity within rat thymus was studied by a panel of 13 monoclonal antibodies (mAbs) raised to thymic epithelial (TE) cells and mesenchymal stroma. Based on their anatomical distribution patterns observed with immunohistological techniques on frozen sections and double immunostaining using anti-keratin antibodies to identify epithelium, they were subdivided into five groups: (i) pan TE cells antibodies (R-MC 2, 3 and 8); (ii) cortical TE cells antibodies (R-MC 13-17); (iii) antibodies detecting subcapsular and subtrabecular TE cells and most medullary TE cells (R-MC 18-20); (iv) antibody to Hassall's corpuscles (HC) and a small subpopulation of medullary TE cells (R-MC 22); (v) mesenchymal stroma antibody (R-MC 23). The obtained results show phenotypic heterogeneity of rat thymic epithelium and its distinction compared to mesodermal-derived compartment.