Double labeled-antigen method for demonstration of intracellular antigens in paraffin-embedded tissues

Abstract

A double 'labeled-antigen' method has been developed for the simultaneous staining of both κ and λ light chains in fixed paraffin sections. The method is a two step procedure utilizing a mixture of antisera against κ and λ light chains in the first stage, followed by the addition of a mixture of κ antigen labeled with horseradish peroxidase and λ antigen labeled with alkaline phosphatase. The selection of substrates yielding reaction products of contrasting color enabled the observer to distinguish κ-containing cells (brown) from λ-containing cells (blue). Reactive plasma cells stained either pure brown (κ) or clear blue (λ) in a ratio of 1.5:1. Blood vessels containing serum immunoglobulins showed a mixed brown-blue reaction, as did the Reed-Sternberg cells of some cases of Hodgkin's disease. The advantages of this double labeled-antigen method over previously reported methods for achieving double staining are discussed.