The labeled antigen method of immunoenzymatic staining.

A two stage immunohistological technique (the "labeled antigen" procedure) has been assessed for the detection of a variety of human and animal cytoplasmic constituents in tissue sections. In this method specific antiserum is followed by antigen complexed to horseradish peroxidase or to alkaline phosphatase. The primary antibody acts bivalently, linking the labeled antigen to antigen in the tissue section. The major advantage of this technique is that nonantigen specific antibody in the primary antiserum cannot cause nonspecific staining since it has no affinity for the antigen:enzyme complex. Consequently the specificity of the reaction is assured, background staining is minimized and the total staining time (from wax section to mounted slide) can be reduced to as little as 30 min. Further advantages include the possibility of labeling Ig allotypes and the high efficiency of enzyme utilization. Covalent human IgG:horseradish peroxidase complexes can also be used in a triple sandwich in conjunction with human anti-viral or autoimmune antibodies.