Division of Radiooncology, Deutsches Krebsforschungszentrum, 69120 Heidelberg, Germany
Nonspecific staining in immunohistology can be a multifactorial problem and may occur to variable degrees. Because the so-called “background” reactions will affect the interpretation of results, appropriate controls are necessary to recognize the underlying reasons and to find out solutions to prevent nonspecificity. In the case of enzymes as markers, endogenous enzyme activities (e.g. peroxidases, alkaline phosphatases) should be blocked to avoid interference with specific immunostaining.