Sensitivity and background staining of the unlabeled antibody enzyme (PAP) method. new approaches to the investigation of the effects of non-immune serum, primary antiserum concentration and pronase digestion using formalin fixed paraffin embedded material.

The effect of primary antibody concentration, non-immune serum, and pronase digestion on the stainability of immunoglobulin containing cells (plasma cells) and background stainability was investigated using the peroxidase-antiperoxidase (PAP) method and antigens consisting of formalin fixed paraffin embedded maxillary mucosa, colonic mucosa, inflammatory synovia and soft-tissue plasmocytoma. The effect of primary anti-serum concentration and non-immune serum on cell and background stainability was smaller, but pronase digestion clearly improved positive stainability and reduced background stainability.