The use of antigen-antibody precipitates for specific detection of antigens in tissue sections.

Antigen—antibody precipitates, prepared either in solution in antibody excess or by cutting precipitin lines from immunoelectrophoretic plates have been shown to bind specifically to the homologous antigen in tissue sections. This finding has been used as the basis of an immunofluorescent technique in which antigen—antibody precipitates are applied to a section and then stained with a fluorescein-conjugated antiglobulin reagent. The technique allows the localization of antigens in tissue even where they are not characterized or purified and where monospecific antisera are not available.