Antigen-binding specificity of isolated cell-surface immunoglobulin from thymus cells activated to histocompatibility antigens.

Lactoperoxidase-catalyzed radioiodination of cell-surface proteins was used in the isolation of cell-surface immunoglobulin from thymus-derived thoracic duct lymphocytes activated to histocompatibility-2 antigens. Immunoglobulin was identified by specific precipitation with antiserum to mouse immunoglobulin. Polyacrylamide gel electrophoresis of reduced and alkylated precipitates showed that the immunoglobulin molecules possessed mu-type heavy chains and light chains. Cell-surface immunoglobulin isolated from thymus-derived cells activated to histocompatibility-2 antigens possessed binding specificity for the activating antigens.