Characterization of the molecules involved in thymocyte thymic epithelial cell adhesion

Cell to cell adhesion is important for mechanisms of cellular recognition, growth, and differentiation. The identification of molecules involved in these interactions is necessary in order to understand the molecular basis of these processes. We have previously described the development of two different thymic epithelial cell lines (TECS and TECL). Using an assay with radiolabeled thymocytes we found that thymocytes can adhere specifically to these thymic epithelial cells. This adhesion is trypsin sensitive, suggesting that involvement of specific cell surface proteins. In the present study we further characterize and begin identification of the molecules involved in this interaction. We found that thymocyte binding to thymic epithelial cells requires the presence of Ca2+ and Mg2+ and is mediated by a molecule greater than 10,000 MW. Also, we identified several antibodies which inhibit the adhesion of thymocytes to TECS. The membrane nature of the molecule mediating this interaction was confirmed by the ability of thymocyte membranes to block the inhibitory antibodies.