EXPRESSION OF A CANDIDATE CADHERIN IN T-LYMPHOCYTES

Cadherins are homotypic adhesion molecules that classically mediate in teractions between cells of the same type in solid tissues, In additio n, E-cadherin is able to support homotypic adhesion of epidermal Lange rhans cells to keratinocytes (Tang, A., Amagai, M., Granger, L. G., St anley, J. R. & Udey. M. C. (1993) Nature (London) 361, 82-85) and hete rotypic adhesion of mucosal epithelial cells to E-cadherin negative in testinal intraepithelial T lymphocytes. Thus, we hypothesized that cad herins may play a wider role in cell-to-cell adhesion events involving T lymphocytes. We searched for a cadherin or cadherins in T lymphocyt es with a pan-cadherin antiserum and antisera against alpha- or beta-c atenin, molecules known to associate with the cytoplasmic domain of ca dherins, The anti-beta-catenin antisera coimmunoprecipitated a radiola beled species in T-lymphocyte lines that had a molecular mass of 129 k Da and was specifically immunoblotted with the pan-cadherin antiserum, Also, the pan cadherin antiserum directly immunoprecipitated a 129 kD a radiolabeled species from an I-125 surface-labeled Jurkat human T-ce ll leukemic cell line. After V8 protease digestion, the peptide map of this pan-cadherin immunoprecipitated, 129-kDa species exactly matched that of the 129-kDa species coimmunoprecipitated with the beta-cateni n antiserum, These results demonstrate that T lymphocytes express a ca tenin-associated protein that appears to be a member of the cadherin s uperfamily and may contribute to T cell-mediated immune surveillance.