Detection of thymic surface antigens and radioactive labeling of mouse lymphoid cells

A method for the permanent and simultaneous detection of tissue-specific surface antigens and internal radioactive labeling of mouse lymphoid cells is described. Target cells were first reacted with a mouse-derived 'antithymocyte serum', incubated with peroxidase-conjugated rabbit serum against mouse immunoglobulins and placed in substrate solution that leads to staining of the antigen-positive cells. Radioactive labeling was demonstrated by autoradiography performed after the antigen assay. More than 90% of antigen-positive thymocytes could be specifically stained in the assay without staining of similarly treated antigen-negative cells. Autoradiographic grains could be detected over both antigen-positive and antigen-negative cells.