Cytokeratin 8 & 18

Cytokeratin 8 belongs to the Type II (basic) subfamily of high molecular-weight keratins and exists in combination with Cytokeratin 18 (Type I [acidic] subfamily of low molecular weight keratins). They are perhaps the most commonly found products of the intermediate filament gene family, and are expressed in single-layer epithelial tissues of the body.

Cytokeratins 8 and 18 can be found in most simple epithelium (e.g., thyroid, female breast, gastrointestinal tract, and respiratory tract). Adenocarcinomas and most Non-keratinizing Squamous Carcinomas will stain, but Keratinizing Squamous Carcinomas will not. This antibody is used when attempting to demonstrate the presence of Paget cells; there is very little keratin 18 in the normal epidermis so only Paget cells will stain. This approach facilitates the interpretation using immunostains and is more sensitive than mucin histochemistry.

Anti-Cytokeratin 8 & 18 is a cocktail of mouse monoclonal antibodies derived from cell culture supernatant that is concentrated, dialyzed, filter sterilized and diluted in buffer pH 7.5, containing BSA and sodium azide as a preservative.

1. Angus B, Purvis J, et al. Journal of Pathology. 1987;155:377-384
2. Corson JM, Pathol Annual. 1986; 21(part 2):47-81
3. Sasaki M, et al. Histopathology. 1998;Mar;32(3):199-208

1. Cut and mount 3-4 micron formalin-fixed paraffin-embedded tissues on positive charged slides.
2. Air dry for 2 hours at 58° C.
3. Deparaffinize, dehydrate and rehydrate tissues.
4. Subject tissues to heat epitope retrieval using a suitable retrieval solution such as ImmunoDNA Retriever with Citrate (BSB 0020-BSB 0023) or EDTA (BSB 0030-BSB 0033).
5. Any of three heating methods may be used:
   • Electric Pressure Cooker
     Place standoff rack at base of pressure cooker. Add 1-2 inches of distilled water to the pressure cooker and turn heat to high, and incubate for 15 minutes. Open and immediately transfer slides to room temperature.
   • Water Bath Method
     Place tissues/slides in a pre-warmed staining dish or coplin jar containing the ImmunoDNA Retriever with Citrate or EDTA in a water bath set at 95°-99° C. Incubate for 30-60 minutes.
   • Conventional Steamer Method
     Place tissues/slides in a pre-warmed staining dish or coplin jar containing the ImmunoDNA Retriever with Citrate or EDTA in a Steamer, cover and steam for 30-60 minutes.
6. After heat treatment, transfer slides in ImmunoDNA Retriever with Citrate or EDTA to room temperature and let stand for 15-20 minutes.
7. Wash slides with IHC wash buffer or DI water.
8. Continue IHC staining protocol.