Immunocytochemistry

Immunocytochemistry provides an accurate way of localizing antigens in situ in tissue sections or cell preparations using antibodies combined with a label that can be identified microscopically. The most frequently used labels are fluorescent compounds that can be excited by light of specific wavelength, enzymes that can act on a specific substrate with a chromogen to give a colored end-product, and colloidal gold (for electron microscopy). Antibodies are applied to tissue preparations, often in a series of layers, one applied antibody acting as an antigen for the next (antispecies) antibody to build up the amount of label at the original site of reaction.