AE1/AE3 is an antibody cocktail that is used in immunohistochemistry, being generally positive in the cytoplasm of carcinomas (cancers of epithelial origin).
The antibody cocktail binds to cytokeratin 1 - 8, 10, 14 - 16 and 19 (but not CK17 or CK18).
It is therefore used as a marker of carcinomas, such as depth of invasion and metastases. For example, it is both relatively sensitive and specific for the detection of breast cancer metastasis to sentinel lymph nodes.
It may cross-react with GFAP, leading to aberrant staining of glial tumors such as ependymoma, glioblastoma, and schwannoma.
It may also stain myofibroblasts and smooth muscle cells.
Furthermore, it may stain nodal epithelial cells that have contaminated a tumor from the recent biopsy.