Immunochemical Analysis of the T Cell-Specific Antigens

During the First International Workshop on Human Leucocyte Differentiation Antigens, eight T cell-specific clusters of differentiation were defined serologically using 70 monoclonal antibodies tested on a large panel of target cells by each of the participating laboratories as described in the joint report of the Workshop (1). Immunochemical analysis of the cell surface antigens recognized by these monoclonal antibodies, performed by two laboratories, showed a strong correlation with the clusters established by the serological analysis (2,3). There are certain limitations in the interpretation of immunochemical results due to the weak affinity of some antibodies to detergent-solubilized antigens under the conditions used for immunoprecipitation. However, the demonstration that two monoclonal antibodies bind to the same cell surface molecule provides the strongest evidence that they belong in the same cluster of differentiation. For this reason, each of the monoclonal antibodies included in the T cell section of the second Workshop was analyzed for its ability to immunoprecipitate specific radiolabeled cell surface T cell antigens. This study provides a molecular basis for interpreting the serological and functional studies performed during the Workshop.