A rapid and simple hapten conjugation method for monoclonal antibodies to be used in immunoenzyme single and double staining procedures

A rapid and simple method was developed for the haptenization of monoclonal antibodies (MAbs), to be used in immunoenzyme single and double staining techniques. Using this method minute amounts of MAbs can be haptenized without purification of the antibody or removal of the excess hapten. The haptenized MAb can be ready for use with 2.5 h. The method consists of a direct incubation of the antibody with the haptenizing agent and subsequent addition of an amino acid solution to stop the reaction. Commonly available reagents were tested, of which dinitrofluorobenzene, trinitrobenzene sulfonic acid and an oxazolone derivative gave the best results. The procedure was evaluated by using MAbs directed against lymphoid cell surface membrane antigens in an indirect immunoenzyme staining on frozen sections using peroxidase or alkaline phosphatase-conjugated anti-hapten antibodies as second step antibody. It was found that those MAbs, which show good staining results in conventional indirect immunoenzyme procedures, can also be used successfully after haptenization in single as well as double staining procedures. Combination of haptenized and biotynilated MAbs gave good results when weakly reactive MAbs had to be included in immunoenzyme double staining.