Effects of primary antiserum dilution on staining of "antigenrich" tissues with the peroxidase antiperoxidase technique.

The effect of primary antiserum dilution on staining results with the peroxidase antiperoxidase method were investigated using frozen sections of perfused rat cerebellum and optic nerve. Results comparable to formalin fixed and paraffin embedded tissue were attainable only when low antiserum concentrations were used. Optimal staining of antigen rich tissue, such as frozen sections, with the peroxidase antiperoxidase method required low antiserum concentrations apparently to minimize the binding of both antigen-binding fragments of the bridging antibody to the tissue bound antiserum. It appears that low antiserum concentration insures that sufficient bridge antibody molecules will be only singly bound and thus free to attach the peroxidase antiperoxidase complex.