E receptors and T antigens are different antigenic entities on human T lymphocytes.

ATS contains antibodies of different specificity directed against E receptors and T specific antigens, respectively. E-receptors are trypsin-sensitive, T-antigens are trypsin-resistant. Absorption of ATS with trypsinized thymocytes thus removes anti-T, but leaves anti-E antibodies unaffected. The rosette inhibitory potential of the absorbed antiserum (anti-E) remains unaltered. Immunization with trypsinized thymocytes on the other hand results in the production of anti T-cell sera highly specific in immunofluorescence and cytotoxicity tests without contaminating anti-E antibodies and, therefore, also lacking any rosette inhibitory capacity. E receptors and T antigens are independently mobile within the cell membrane as shown by differential capping.