Use of radioactive antibodies for characterizing antigens and application to the study of flagella synthesis.

A simple rapid immunochemical procedure has been developed which provides information about the qualitative and quantitative nature of antigens. It involves the use of purified radioactive ((125)I-labeled) antibodies. The amount of antibody bound to the antigen is determined by filtering the mixture through diethylaminoethyl (DEAE)-cellulose paper. All of the antigen, as well as the antibody complexed with it, is trapped on the paper, whereas free antibody is removed by repeated washing. This technique has been applied to the study of three immune systems, bovine serum albumin, Escherichia coli tryptophan synthetase B protein, and Bacillus subtilis flagella. The results obtained by the DEAE-antibody binding technique were comparable, in terms of sensitivity, specificity, and accuracy, to data obtained by microcomplement fixation and precipitin methods. The assay was used to measure the kinetics of flagella regeneration in B. subtilis.