Tritium radiolabeling of antibodies to high specific activity with N-succinimidyl [2,3-3H] propionate: use in detecting monoclonal antibodies.

A simple method has been established for tritium labeling immunoglobulins. This label avoids certain disadvantages of 125iodine such as high radiation hazard and requirement for frequent labeling owing to the short half-life of this isotope. High specific activities (range 1.8-9.0 cpm/mu g protein) were obtained with no loss of functional activity as demonstrated by passive hemagglutination. The labeled conjugate is especially suitable for detection of activity in hybridoma supernatants by indirect binding assay. Adapted to microtiter plates, the method is suitable for large numbers of samples, e.g. up to 800 supernatants may be examined daily. The utility and advantages of the binding assay with respect to reproducibility, sensitivity, binding kinetics, easy and rapid performance are described.