The application of the avidin-biotin technique to previously stained histological sections.

Using the sensitive avidin-biotin peroxidase technique, a wide variety of tissue antigens can be detected in standard histological sections of both normal and pathological tissues previously stained with hematoxylin and eosin. There appears to be no detectable reduction of sensitivity with this method of "restaining" compared to the standard immunoperoxidase procedure applied to unstained tissue sections. This technique makes it possible for retrospective identification of tissue antigens when insufficient unstained material is available.