Abstract
Endogenous immunoglobulin in tissue sections pose a problem in immuno-histo-chemical techniques employing homologous antibody as primary reagents and enzyme-labelled anti-immunoglobulin for the development. A method for the blocking of endogenous immunoglobulin in human tissue sections by incubation with monomeric pepsin fragments (Fab') of rabbit anti-human immunoglobulin before applying monoclonal antibody was evaluated for the screening of human monoclonal antibody. It was initially demonstrated that Fab' rabbit anti-human IgM and anti-IgG could block endogenous immunoglobulin in human IgM and IgG producing tumors thereby abolishing the binding of subsequently applied peroxidase-labelled anti-IgM or anti-IgG. Frozen sections of human colo-rectal adenocarcinomas show a variable background staining caused by the endogenous immunoglobulin. The background completely disappeared in the IgM system by preincubation with Fab' anti-IgM while the background was clearly reduced but not abolished in the IgG system. A human hybridoma supernatant containing IgM reactive with colo-rectal adenocarcinoma could easily be screened on frozen sections using this method. This approach should be generally useful for the screening of human antibody on human tissue sections.
Get full access to this article
View all access options for this article.