This immunohistochemistry protein blocker is specifically designed for immunohistochemical staining where detection occurs using an immunoenzymatic reaction with substrate, i.e. peroxidase (HEP) with diaminobenzidine (DAB). This product specifically inhibits non-specific staining of IHC detection reagents. It may be used on various specimens, including cultured cells and primary tissue to lower background staining. Optimum performance is achieved using this product undiluted.