I am staining for cytochrome oxidase in human brain tissue and need to eliminate the background neuromelanin staining caused by the DAB in the cytochrome -c solution.
only interested in the matter (and DAB in an other consensus), unfortunately no practical experience. But I would like to point you to search via GOOGLE entering search words (as they follow)
destain dab
You'll see (approx.14.500 results found) that the matter is not that easy (because of controversial standpoints) but perhaps within the first 10-20 results you will find the solution of your problem (be it pos - or - unfortunately - negative) Best wishes and good luck.