Immunochemical Characterization of Rat T Lymphocyte Antigens

Rat thymus and T cell-surface antigens were analyzed using one-and two-dimensional polyacrylamide gel electrophoresis (PAGE). For this purpose, cell-surface glycoproteins of rat lymphocytes were radiolabeled with 125I by lactoperoxidase, purified on a Lentil lectin-coupled Sepharose 4B column, and were reacted with anti-rat T lymphocyte xenoantiserum (ATLS). When 125I labeled glycoproteins of rat thymus and T cells were immunoprecipitated with unabsorbed ATLS and analyzed by one-dimensional SDS-PAGE, a number of antigenic components with different molecular weights (M. W. ) were found on these cells. Thus, these components comprised glycoproteins with M. W. of 150K. 130K, 94K, 90K, 75K, 67K, 62K, 57K, 55K, 50K, 45K, 43K and 30K daltons, respectively. Among these components, 90K (T90), 67K (T67), 62K (T62) and 43K (T43) M. W. glycoproteins appeared specific for rat thymus and T cells, because these components could be found on rat thymus and T cells as well as on thymoma cells but not on rat bone marrow and leukemic B cells (KNL-14). Absorption studies demonstrated that these antigenic components did not exist in non-lymphoid tissues, including rat brain, liver, kidney and fibrosarcoma cells (KMT-17). Two dimensional PAGE analysis of these rat T cell-specific glycoproteins clearly showed that, while T67 and T62, the latter being found in some preparations of rat T cell glycoproteins, exhibited marked charge heterogeneity with pI between 5.8 and 7.5, T90 and T43 were identified as acidic glycoproteins with pI of 5.7 and 5.5, respectively. The anti-rat Tcell serum (ATLS) used in this study was also cross-reactive with mouse thymus and T cells, from which the antiserum immunoprecipitated cell-surface glycoproteins similar to found on rat thymus and T cells. These data clearly suggest that rat thymus and T cells possess a complex antigenic make-up on their cell surfaces, comparable to that of murine T cells with a variety of Ly antigen systems