Product details
Synonyms = Keratin-17; KRT17; PCHC1, K17; Keratin Type I Cytoskeletal 17
Antibody type = Recombinant Rabbit monoclonal / IgG
Clone = MSVA-117R
Positive control = Prostate: A strong CK17 staining should be seen in basal cells while acinar cells remain negative.
Negative control = Colon: CK17 staining should be absent in all cells.
Cellular localization = Cytoplasmic
Reactivity = Human
Application = Immunohistochemistry
Dilution = 1:100 – 1:200
Intended Use = Research Use Only
Relevance of Antibody
Cytokeratin 17 is Marker for basal cells in many tissues.
Biology Behind
Keratin 17 (CK17), also termed keratin 17 (KRT17) is an 48 kDa type I cytokeratin coded by the KRT17 gene at 17q21.2. CK17 is part of the cytoskeletal scaffold within epithelial cells, which contributes to the cell architecture and provides the cells with the ability to withstand mechanical stress. It is primarily found in nail beds, sebaceous glands, hair follicles, and other epidermal appendages. CK17 is usually absent in squamous epithelium but is inducible under stressful conditions such as skin injury, viral infections or other inflammatory diseases. Mutations in CK17 are associated with pachyonychia congenita type 2 and steatocystoma multiplex.
Staining Pattern in Normal Tissues
Images describing the Cytokeratin 17 staining pattern in normal tissues obtained by the antibody MSVA-117R are shown in our “Normal Tissue Gallery”.
| Brain | Cerebrum | Negative. |
| Cerebellum | Negative. | |
| Endocrine Tissues | Thyroid | Negative. |
| Parathyroid | Negative. | |
| Adrenal gland | Negative. | |
| Pituitary gland | Negative. | |
| Respiratory system | Respiratory epithelium | Strong CK17 staining of basal cells. |
| Lung | Negative. | |
| Gastrointestinal Tract | Salivary glands | Strong CK17 staining of basal cells of excretory ducts and of myoepithelial cells. Glandular cells are not stained. |
| Esophagus | Few basal cells show weak to moderate staining in some of the samples. | |
| Stomach | Negative. | |
| Colon | Negative. | |
| Duodenum | Negative. | |
| Rectum | Negative. | |
| Small intestine | Negative. | |
| Liver | Negative. | |
| Gallbladder | Negative. | |
| Pancreas | Strong CK17 staining of a subset of small excretory ducts while intercalated ducts and large excretory ducts are CK17 negative. | |
| Genitourinary | Kidney | A subset of tubular cells can show strong CK17 positivity in a subset of samples. |
| Urothelium | CK17 staining predominates in basal cells and is only faint (not always seen) in higher cell layers). | |
| Male genital | Prostate | Strong CK17 staining of basal cells. |
| Seminal vesicles | Strong CK17 staining of most basal cells. | |
| Testis | Negative. | |
| Epididymis | Strong CK17 staining of basal cells in the corpus epididymis. | |
| Female genital | Breast | CK17 staining of basal/myoepithelial cells is more prominent in excretory ducts than in small glands. |
| Uterus, myometrium | Negative. | |
| Uterus, ectocervix | Negative. | |
| Uterus endocervix | Strong CK17 staining of basal cells can be seen in some samples. | |
| Uterus, endometrium | Negative. | |
| Fallopian Tube | Negative. | |
| Ovary | Negative. | |
| Placenta early | Negative. | |
| Placenta mature | Negative. | |
| Amnion | Strong CK17 staining. | |
| Chorion | Strong CK17 staining. | |
| Skin | Epidermis | Squamous epithelium of the skin surface is usually negative but focal staining of groups of cells can occur. |
| Sebaceous glands | Strong CK17 staining of hair follicles and of sebaceous glands. | |
| Muscle/connective tissue | Heart muscle | Negative. |
| Skeletal muscle | Negative. | |
| Smooth muscle | Negative. | |
| Vessel walls | Negative. | |
| Fat | Negative. | |
| Stroma | Negative. | |
| Endothelium | Negative. | |
| Bone marrow/lymphoid | Bone marrow | Negative. |
| Lymph node | Negative. | |
| Spleen | Negative. | |
| Thymus | A large subset of thymic epithelial cells (including corpuscles of Hassall’s) show significant CK17 staining. Lymphocytes are negative. | |
| Tonsil | Strong CK17 staining of basal and suprabasal cells of crypt epithelium while surface squamous epithelium is either negative or shows a rather weak staining of basal cells. Lymphocytes are negative. | |
| Remarks | CK17 staining predominantly occurs in basal cell layers of various tissues. |
These findings are largely consistent with the RNA data described in the Human Protein Atlas (Tissue expression Cytokeratin 17).
Positive control = Prostate: A strong CK17 staining should be seen in basal cells while acinar cells remain negative.
Negative control = Colon: CK17 staining should be absent in all cells.
Staining Pattern in Relevant Tumor Types
CK17 is primarily expressed in squamous cell carcinomas of various organs of origin and in urothelial carcinomas. CK17 expression may also occur in other tumors.
The TCGA findings on Cytokeratin 17 RNA expression in different tumor categories have been summarized in the Human Protein Atlas.
Compatibility of Antibodies
No data available at the moment
Protocol Recommendations
IHC users have different preferences on how the stains should look like. Some prefer high staining intensity of the target stain and even accept some background. Others favor absolute specificity and lighter target stains. Factors that invariably lead to more intense staining include higher concentration of the antibody and visualization tools, longer incubation time, higher temperature during incubation, higher temperature and longer duration of the heat induced epitope retrieval (slide pretreatment). The impact of the pH during slide pretreatment has variable effects and depends on the antibody and the target protein.
All images and data shown here and in our image galleries are obtained by the manual protocol described below. Other protocols resulting in equivalent staining are described as well.
Manual protocol
Freshly cut sections should be used (less than 10 days between cutting and staining). Heat-induced antigen retrieval for 5 minutes in an autoclave at 121°C in pH 7,8 Target Retrieval Solution buffer. Apply MSVA-117R at a dilution of 1:150 at 37°C for 60 minutes. Visualization of bound antibody by the EnVision Kit (Dako, Agilent) according to the manufacturer’s directions.
Potential Research Applications
- The diagnostic and prognostic relevance of CK17 expression in tumors and in preneoplastic disease needs to be investigated.
Evidence for Antibody Specificity in IHC
There are two ways how the specificity of antibodies can be documented for immunohistochemistry on formalin fixed tissues. These are: 1. Comparison with a second independent method for target expression measurement across a large number of different tissue types (orthogonal strategy), and 2. Comparison with one or several independent antibodies for the same target and showing that all positive staining results are also seen with other antibodies for the same target (independent antibody strategy).
Orthogonal validation: For the antibody MSVA-117R specificity is suggested by the strong concordance of the immunostaining data with data from three independent RNA screening studies, including the Human Protein Atlas (HPA) RNA-seq tissue dataset, the FANTOM5 project, and the Genotype-Tissue Expression (GTEx) project, which are all summarized in the Human Protein Atlas (Tissue expression Cytokeratin 17. CK17 positivity by MSVA-117R is detectable in all tissues with documented CK17 RNA expression (salivary glands, esophagus, urothelium, prostate, seminal vesicles, epididymis, breast, cervix uteri, skin, thymus, tonsil). Tissues without previously documented CK17 RNA expression but CK17 positivity by MSVA-117R had either very few positive cells that were probably not detected in RNA studies (pancreas, kidney) or were previously not analyzed on the RNA level (amnion and chorion cells, bronchial glands, paranasal sinus).
Comparison of antibodies: True expression of CK17 in all cell types found CK17 positive by MSVA-117R is corroborated by identical stainings obtained by another commercially available independent antibody (termed “validation antibody”).
