There is an endogenous peroxidase blocking method using glucose oxidase + glucose which works very well for frozen sections and also FFPE tissues. It is an enzymatic chemical reaction that produces a slow, steady rate of hydrogen peroxide to remove endogenous peroxidase and pseudoperoxidaes without damaging mophology in frozen sections. The sodium azide contributes to the peroxidase blocking. It has been used successfully by people having trouble removing these peroxidases from FFPE tissues. Do not try to buy the glucose from Sigma as they discontinued this particular glucose.
Glucose Oxidase Peroxidase Block (GLUOX)
beta D(+) glucose, 97% pure from ICN Biomedicals Corp #100953 0.180g
glucose oxidase (Sigma G6641) 0.005g
sodium azide 0.0065g
Dulbeccos PBS (Sigma, no Mg or Ca added) 50 ml
We made up a large stock of the DPBS with sodium azide to avoid weighing out sodium azide in such small amounts, and referred to this buffer as the GLUOX buffer.
DO NOT PREHEAT THE BLOCKING SOLUTION BEFORE USE.
1. Immerse deparaffinized section in the GLUOX mixture and incubate for 30 min to 1 hour. One hour may be advisable for FFPE tissue, in the literature and for frozen sections, time was 30 min - 1 hr.
2. Rinse 3X in DPBS and proceed with IHC method.
Andrew SM, Jasani B. An improved method for the inhibition of endogenous peroxidase non-deleterious to lymphocyte surface markers. Application to immunoperoxidae studies on eosinophil-rich tissue preparations. Histochem J 19:426-430, 1987.
Gayle M. Callis
Histonet mailing list