Peroxidase blocking reagent

After the sections were deparaffinized in xylene and rehydrated through a series of graded ethanol solutions, antigenic retrieval was performed by immersing the sections in 0.01 mM sodium citrate (pH 6.0) and heating in an microwave oven (100 °C) for 9 min. Deparaffinized sections were incubated with peroxidase-blocking reagent (Biogenex, CA, USA) for 9 min in a humidified chamber to block endogenous peroxidase activity. After blocking nonspecific binding sites with nonspecific staining blocking reagent (Vector Laboratories, Burlingame, CA, USA) for 30 min, the sections were incubated with primary antibodies at 4 °C overnight. Subsequently, peroxidase-conjugated secondary antibodies (Vector Laboratories) and 3,3-diaminobenzine-tetrachloride (DAB; Vector Laboratories) were used according to the manufacturer’s instructions. The sections were counterstained with hematoxylin and observed under a microscope.