What are Cytokeratin’s?
Cytokeratin’s are proteins and an important component of the intermediate filaments found within the cytoplasm of epithelial cells. Epithelial cells cover the surface of the body as well as line organs and body cavities. They perform many functions including protection, secretion, absorption, filtration diffusion and sensory reception.
What are Cytokeratin’s 5, 6?
Cytokeratin’s are grouped into various types ( 1 through 4). Their classification is dependent on their structure and function. Cytokeratin 5,6 are classified as Type 11, high molecular weight keratins. CK5,6 proteins are found in normal tissues of the breast, prostate, skin, esophagus and mesothelium (protective membrane covering the lungs, abdomen, heart and testes).
Why do pathologists order “Cytokeratin’s”?
It is very important for pathologists to identify the origin of a patient’s tumor. Pathologists need to determine if the tumor originated in the organ from which the tissue sample was taken (primary site) or if the tumor developed in another area of the body (secondary tumor). Pathologists use both the morphology of the tissue along with various immunohistochemistry markers in diagnosis. Immunohistochemistry staining of Cytokeratin’s is important in the classification of carcinomas of unknown primary.
CK5,6 is often used in classification of breast, lung and prostate cancer. The immunohistochemistry staining reaction in the patient’s tissue provides the pathologist with important information used to distinguish between different types of breast cancer and lung cancer. Pathologists use both positive staining and lack of staining results as diagnostic criteria in prostate cases.
Incidence of cancers associated with use of Cytokeratin 5 & 6
Breast cancer is the most frequent malignancy in women (global). It represents about 25% of all cancers reported in women. In 2020 Belgium reported the highest rate of breast cancer of any reporting nation (statistics compiled by the World Cancer Research Fund).
Prostate cancer is the second most frequent malignancy in men (global). Sixty percent of all cases are diagnosed in men over the age of 65 . The highest rates of prostate cancer are reported in Australia and New Zealand, followed by Northern, Western Europe and then North America.
Lung cancer is the most common cancer occurring in men and the third most common cancer in women (global). Lung cancers represent approximately 13% of all cancers. In 2018 Hungary reported the highest rate of lung cancer of any reporting nation (statistics complied by the World Cancer Research Fund).
End User Resource
NordicQC, a globally recognized leader in external quality assurance gave Cell Marque , Cytokeratin 5, 6, clones D5/16B4 an “optimal” score amongst the available CK5.6 antibodies in their most recent assessment. Our customers rely on NordiQc as a source of unbiased reporting and depend on the NordiQC findings when determining the antibodies they will purchase.
Please see conclusion findings for most recent Nordic QC assessment https://www.nordiqc.org/downloads/assessments/38_87.pdf
“ The mAb clones XM26, D5/16B4, LL002 and the rmAb clone SP53 could all be used to obtain an optimal staining result. The mAb clone XM26 against CK5 gave the highest proportion of sufficient and optimal results and could be applied on all the 3 main IHC platforms from Ventana, Dako and Leica. HIER, preferable in an alkaline buffer, is mandatory for all clones. The mAb clone 34BE12 cannot be used as general marker for CK-HMW due to cross-reaction with CK-LMW. Esophagus is recommended as positive tissue control. For Abs against CK5 and CK5/6, virtually all the squamous epithelial cells must show a moderate to strong cytoplasmic staining reaction. Liver or appendix must be used as negative tissue controls, in which no staining must be seen.”
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