Comparison between peroxidase-conjugated antigen or antibody and peroxidase-anti-peroxidase complex in a postembedding procedure.

The staining efficiency of peroxidase labeled immunoglobulin conjugate, used either as antigen or as antibody, has been compared with that of peroxidase-anti-peroxidase complex (PAP) on ultrathin sections of araldite embedded material. The conjugate gave positive results in a two layer method as well as in a three layer method when used as antibody. No staining was observed when it was used as antigen. The conjugation seemed to impair the antigenic reactivity of immunoglobulin. The conjugate when used as antibody in the three layer method gave approximately the same staining efficiency as PAP.