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KRT8 / Keratin, type II cytoskeletal 8 · IHC design guide
Design Immunohistochemistry for KRT8
KRT8 IHC shows cytoplasmic and membranous staining in glandular epithelia, renal tubules and pneumocytes (HPA tissue IHC). This guide helps plan paraffin-section controls, chromogenic detection and compartment-aware scoring.
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
KRT8 Immunohistochemistry Experimental Design Guide
Expected localisation, validated protocols, controls and antibodies — the at-a-glance facts below, then the full design guide.
Must know before staining
| Expected localisation | Cytoplasmic and membranous staining (HPA tissue IHC) | |
| Staining pattern | Glandular epithelia, renal tubules and pneumocytes stain in the cytoplasm and at membranes (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet M01421-2) | |
| Positive control | Appendix+4 more · see all | |
| Negative control | Adipose tissue+4 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation consistent across sections. (standard IHC practice; not target-specific) | |
| Caveat | Esophageal squamous cells may lack staining (HPA tissue IHC) | |
| Regulation | No stimulus-dependent regulator is specified (UniProt) | |
| Isoform / epitope | 2 isoforms; epitope impact is undetermined (UniProt) |
Section 1
Recommended KRT8 IHC & IF Protocols
Compare the catalog antibody’s IHC-P protocol (datasheet: M01421-2) with the published KRT8 chromogenic IHC protocol (PMC5855799).
| Sample | Paraffin-embedded human lung cancer tissue; fixative not specified (datasheet M01421-2) |
| Fixation | Image fixative and duration unreported (datasheet M01421-2); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat retrieval: EDTA pH 8.0 (datasheet M01421-2); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet M01421-2) |
| Primary antibody | Rabbit monoclonal (clone CIG-11) anti-KRT8, 1:50 (datasheet M01421-2) |
| Primary incubation | Overnight at 4 °C (datasheet M01421-2) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet M01421-2) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | KRT8-positive staining in endocrine cells of appendix (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic and membranous expression in most glandular epithelia, renal tubules and pneumocytes. No signal in the no-primary control. |
💡Decision noteStart with EDTA pH 8.0 heat retrieval for the catalog antibody (datasheet: M01421-2); the published protocol used pressure-cooker retrieval (PMC5855799).
Section 2
What Is the Expected KRT8 Staining Pattern?
KRT8 is an intermediate-filament protein of simple epithelial cells (UniProt P05787). In paraffin-section IHC, expect cytoplasmic and membranous staining in many glandular epithelia, renal tubules and pneumocytes (HPA tissue IHC). HPA rates its tissue profile Enhanced, with medium consistency between antibody staining and RNA expression (HPA tissue IHC). KRT8 has no transmembrane segment (UniProt P05787 topology), so membranous staining does not by itself imply a membrane-spanning protein.
| Cytoplasmic staining outlines glandular epithelial cells, with some apparent membranous accentuation. | This matches the reported IHC distribution (HPA tissue IHC). Score the specified cell population and compartment together; staining elsewhere in the section does not replace evidence in the intended cells (general IHC practice). |
| Strong staining appears in breast or endometrial glandular cells, or bronchial respiratory epithelial cells. | Each is reported High in those cell types (HPA tissue IHC). These are useful reference patterns, but the reported level describes HPA observations, not a guaranteed intensity for every section or antibody (HPA tissue IHC; general IHC practice). |
| Signal is exclusively extracellular, luminal, or nuclear, without the expected epithelial cytoplasmic pattern. | Recheck localisation and controls before calling it KRT8 (HPA tissue IHC; general IHC practice). UniProt also lists nucleoplasm and nuclear matrix, so nuclear signal alone is suspicious in this IHC context, not proof of an artefact (UniProt P05787). |
| Adipocytes, marrow hematopoietic cells, or esophageal squamous cells stain strongly. | HPA reports KRT8 Not detected in those specified cell populations (HPA tissue IHC). Investigate antibody cross-reactivity or endogenous detection activity; a positive result in one cell type does not make its whole tissue a validated negative control (general IHC practice). |
| The slide has broad haze or no signal in an expected High cell population. | Haze that obscures cell boundaries weakens localisation calls; an empty known-positive population makes a negative test result uninterpretable (general IHC practice). Compare a matched positive section and detection controls before assigning biological absence (HPA tissue IHC; general IHC practice). |
💡Expected KRT8 appearanceCall a section positive when the intended epithelial cells show convincing cytoplasmic staining, possibly with membranous accentuation (HPA tissue IHC); HPA reports High staining in selected glandular and respiratory epithelial cells (HPA tissue IHC). Treat diffuse haze or staining confined to unexpected cells as suspect until controls resolve it (general IHC practice).
| Cell identity and tissue context | HPA reports High staining in specific cells, including appendix endocrine cells and breast glandular cells, while adipocytes and marrow hematopoietic cells are Not detected (HPA tissue IHC). Interpret at the cell level (general IHC practice). |
| Filament localisation and apparent membrane staining | KRT8 forms intermediate filaments with type I keratins, including KRT18 (UniProt P05787). Its reported IHC pattern includes membranous expression, although it has no transmembrane segment (HPA tissue IHC; UniProt P05787 topology). |
| Antibody validation | HPA lists HPA049866, CAB000131 and CAB001696 as IHC Enhanced (HPA antibodies). That supports their recorded staining patterns but does not establish identical performance for every antibody or preparation (HPA antibodies; general IHC practice). |
| IF/ICC Q&A: What pattern should an IF image show? | An intermediate-filament pattern is the supported main location; HPA shows ICC-IF images in A-431, U-251MG, U2OS, CACO-2 and MCF-7 (HPA subcellular). This localisation answers the IF pattern question; it does not supply an IF protocol (HPA subcellular). |
| Situation | Likely cause | Next action |
|---|---|---|
| No staining in a breast glandular or bronchial respiratory epithelial reference section. | Those cells are reported High, so a blank reference section raises concern about assay performance or section quality (HPA tissue IHC; general IHC practice). | Check tissue identity and preservation, antibody and detection controls, then review the IHC antibody's stated conditions; evaluate retrieval only as a general IHC optimisation step (general IHC practice). |
| Diffuse chromogen covers epithelium and surrounding tissue. | Non-specific binding, excess detection signal, or incomplete washing can obscure cell localisation (general IHC practice). | Compare no-primary and detection controls; review blocking, antibody concentration, washing and chromogen development under the assay's standard workflow (general IHC practice). |
| Strong signal appears in HPA-listed Not detected cell populations. | Cross-reactivity or endogenous detection activity is possible; HPA lists esophageal squamous cells and adipocytes as Not detected (HPA tissue IHC; general IHC practice). | Check a no-primary control and the detection system's endogenous-activity control; confirm the result with an independently validated KRT8 antibody if needed (general IHC practice). |
| Only nuclei or luminal material stain, with no epithelial cytoplasmic signal. | The distribution conflicts with HPA's main tissue IHC profile, though UniProt also annotates nuclear locations (HPA tissue IHC; UniProt P05787). | Recheck the intended cells, section morphology and controls. Do not classify nuclear staining as definitively false solely from its compartment (general IHC practice; UniProt P05787). |
| A glandular area stains weakly while nearby cells stain strongly. | HPA's High calls apply to specified cell populations, and its overall tissue profile has medium consistency with RNA expression (HPA tissue IHC). | Identify and score each cell population separately; compare with a matched positive reference before interpreting weak staining as loss of KRT8 (general IHC practice). |
| Results differ between antibodies on adjacent sections. | Different antibody staining can reflect assay performance; HPA's Enhanced status is validation evidence, not a guarantee of identical section-level results (HPA antibodies; general IHC practice). | Compare the same cell types, localisation and controls for both assays, then review each antibody's IHC validation and stated conditions (HPA antibodies; general IHC practice). |
Experiment evidence
IHC & IF images showing KRT8 staining
M01421-2 · IHCIHC analysis of KRT8 using anti-KRT8 antibody (M01421-2). KRT8 was detected in a paraffin-embedded section of human lung cancer tissue. Heat
M01421-2 · IHCIHC analysis of KRT8 using anti-KRT8 antibody (M01421-2). KRT8 was detected in a paraffin-embedded section of human lung cancer tissue. Heat
M01421-2 · IFImmunofluorescent analysis using the Antibody at 1:150 dilution.
M01421-3 · IHCIHC analysis of Cytokeratin 8 using anti-Cytokeratin 8 antibody (M01421-3). Cytokeratin 8 was detected in paraffin-embedded section of human
M01421-3 · IFIF analysis of Cytokeratin 8 using anti-Cytokeratin 8 antibody (M01421-3). Cytokeratin 8 was detected in immunocytochemical section of U20S
PA1240 · IHCIHC analysis of ITGB3 using anti-ITGB3 antibody (PA1240). ITGB3 was detected in a paraffin-embedded section of human intestinal cancer tissu
M01421-6 · IHCHuman colon carcinoma was stained with anti-Cytokeratin 8 rabbit antibody
M01421-6 · IHCMouse stomach was stained with anti-Cytokeratin 8 rabbit antibody
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000170421-KRT8/tissue/cerebral+cortex#imid_14439408
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000170421-KRT8/tissue/colon#imid_14444502
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000170421-KRT8/tissue/liver#imid_14444511
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000170421-KRT8/tissue/kidney#imid_14444512
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody CAB000131; green = KRT8, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody CAB000131; green = KRT8, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for KRT8 IHC & IF
🧪Run bronchus first: respiratory epithelial cells should stain for KRT8 (HPA: High in bronchus respiratory epithelial cells). Use cerebellum granular-layer cells as the negative tissue (HPA: Not detected in cerebellum granular-layer cells); on the bronchus slide, assess adjacent non-epithelial cells for background-only staining, without assuming every such cell is KRT8-negative.
Positive control tissue: Appendix (Endocrine cells, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show KRT8 in A-431, U-251MG, U2OS, CACO-2, MCF-7, with annotated localisation: Intermediate filaments (supported) (HPA subcellular).
Technical controls: Include no-primary (secondary-only), a host- and isotype-matched nonimmune IgG control (caption: rabbit primary), and a KRT8 knockout specimen if available as a biological negative. For chromogenic IHC, quench endogenous peroxidase and check bronchial inflammatory cells for residual signal; for IF, inspect tissue autofluorescence before interpreting staining (standard IHC/IF practice).
⚠️Feasibility: No target-specific fixation window or fixation effect is reported in the supplied evidence; the selected M01421-2 tissue-IHC caption does not state a fixative (selected-SKU caption: fixative not stated). The paraffin-section example uses heat retrieval in EDTA at pH 8.0, but does not establish whether retrieval is essential for other specimens (selected-SKU caption). HPA shows intermediate-filament localisation in ICC-IF images (HPA: subcellular), while the supplied evidence does not establish that IF or frozen sections are easier than paraffin IHC; account for endogenous peroxidase in inflammatory cells when interpreting bronchus staining (standard IHC practice).
HPA tissue IHC evidence for KRT8
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — Medium consistency between antibody staining and RNA expression data.). Rows are taken directly from the HPA tissue chart — click any row's HPA link to view the source.
Positive expression · recommended positive controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Appendix | Endocrine cells | High | Protein (IHC) | HPA → |
| Breast | Glandular cells | High | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | High | Protein (IHC) | HPA → |
| Cervix | Glandular cells | High | Protein (IHC) | HPA → |
| Colon | Endocrine cells | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Adrenal gland | Glandular cells | Not detected | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Caudate | Glial cells | Not detected | Protein (IHC) | HPA → |
| Cerebellum | Cells in granular layer | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced KRT8 IHC Tips
Troubleshoot KRT8 staining in paraffin section IHC by checking retrieval, cell identity, filament localisation and controls before comparing staining scores.
How should I adjust retrieval when KRT8 staining is weak or uneven?
Start with heat mediated retrieval in EDTA at pH 8.0 for this paraffin section assay (datasheet M01421-2). The selected antibody produced staining after that retrieval in a paraffin section of human lung cancer tissue, but the caption does not report a heating time (datasheet M01421-2). If staining is weak, check that sections received uniform heat, cooled consistently and stayed covered by buffer; compare any revised heating time against an identically processed control section (standard IHC practice). Change one retrieval variable at a time, and assess whether increased epithelial signal also raises staining in cells expected to be negative (HPA tissue IHC; standard IHC practice).
Could fixation explain weak KRT8 staining in my paraffin sections?
The selected KRT8 image identifies a paraffin section but does not state its fixative, so target specific fixation sensitivity is unknown (datasheet M01421-2). Record the fixative, fixation duration and processing history for each specimen before attributing weak staining to antigen loss (standard IHC practice). Compare suspect and reference sections using the same EDTA pH 8.0 retrieval and detection workflow, with glandular epithelium assessed in each where present (datasheet M01421-2; HPA tissue IHC). If a processing change improves signal, confirm that cellular pattern and negative controls remain credible; improvement alone does not establish a KRT8 specific fixation mechanism (standard IHC practice).
What KRT8 staining pattern should I accept in tissue sections?
Expect staining associated with epithelial cytoplasm and its filament network: KRT8 is an intermediate filament protein, and HPA reports cytoplasmic and membranous staining in most glandular epithelia, renal tubules and pneumocytes (UniProt P05787; HPA tissue IHC). A peripheral accent can therefore be assessed alongside the cytoplasmic pattern, rather than scored in isolation (HPA tissue IHC; standard IHC practice). UniProt also lists nucleoplasm and nuclear matrix localisation, so a nuclear signal deserves review against cellular morphology and controls before interpretation (UniProt P05787). Compare nearby expected positive epithelial cells with cells expected to lack staining, and investigate diffuse staining that obscures those boundaries (HPA tissue IHC; standard IHC practice).
Why might different KRT8 antibodies produce different IHC patterns?
KRT8 has 2 listed isoforms, and its intermediate filament rod spans residues 91–402; the supplied product caption does not identify the antibody epitope (UniProt P05787; datasheet M01421-2). It is therefore uncertain whether this antibody recognises both isoforms or whether a particular modification affects binding (UniProt P05787; datasheet M01421-2). Several modified residues are listed, including phosphoserines near the amino terminus, but their effect on this IHC assay is unreported (UniProt P05787; datasheet M01421-2). When antibodies disagree, compare their documented epitopes if available, then examine matched sections with the same retrieval, epithelial controls and scoring criteria (standard IHC practice).
How can IF help investigate an ambiguous KRT8 IHC pattern?
Use IF as a separate localisation check, because the selected product evidence describes chromogenic staining of a paraffin section rather than an IF procedure (datasheet M01421-2). Multiplex KRT8 with a marker of the epithelial cell population under study, and inspect whether signals occur in the same cells while keeping single stain controls for spectral overlap (UniProt P05787 function; standard IF practice). Choose fluorophores after checking the specimen’s autofluorescence, and include an unstained control when tissue background is prominent (standard IF practice). KRT8 has no transmembrane segment and is primarily associated with cytoplasmic intermediate filaments, so plan permeabilisation for access to an intracellular epitope while checking that filament structure remains interpretable (UniProt P05787; HPA subcellular; standard IF practice).
How do I reduce background without losing genuine KRT8 staining?
Begin by separating diffuse background from cell shaped epithelial staining; HPA reports cytoplasmic and membranous KRT8 in most glandular epithelia (HPA tissue IHC). The selected caption used 10% goat serum blocking, antibody at 1:50 overnight at 4°C, and a peroxidase linked detection step with DAB (datasheet M01421-2). If background is high, compare a lower primary concentration or shorter incubation on matched sections, while retaining a known positive compartment (standard IHC practice). Include a no primary control, check washes and peroxidase blocking, and judge any improvement against the loss of expected epithelial staining (standard IHC practice; HPA tissue IHC).
How should I quantify KRT8 staining across samples? ⚠ ANSWER MARKED FOR VERIFICATION
Define the tissue compartment and eligible epithelial cells before scoring, because KRT8 expression varies by cell type within tissues (HPA tissue IHC). For chromogenic sections, record the percentage of positive eligible cells and staining intensity, then calculate an H-score consistently if intensity is part of the study question (standard IHC practice). Alternatively, report positive cell density per mm² of evaluable tissue when cell abundance is the outcome, excluding folds, necrosis and unusable edges by a preset rule (standard IHC practice). Normalise comparisons to the same eligible cell population or evaluable area, and process controls and samples with matched retrieval, staining and image settings (standard IHC practice).
How can I distinguish genuine KRT8 staining from IHC artefact?
A credible positive pattern follows identifiable epithelial cells and their cytoplasmic filament compartment; KRT8 is a structural intermediate filament protein, and HPA describes cytoplasmic and membranous staining in glandular epithelia (UniProt P05787; HPA tissue IHC). Review unexpected staining against cell identity: HPA reports no detection in adipocytes or bone marrow hematopoietic cells, while listing high staining in breast glandular cells (HPA tissue IHC). Strong signal confined to section edges or necrotic areas warrants comparison with intact internal tissue and a no primary control (standard IHC practice). If brown deposits persist without primary antibody, investigate endogenous peroxidase activity or detection background before assigning KRT8 positivity (standard IHC practice).
Boster reagents
Best KRT8 / Keratin, type II cytoskeletal 8 IHC Antibodies
Anti-KRT8 antibodies have IHC images from human, mouse and rat tissues (catalog IHC captions), plus IF images from human and rat sections and cultured cells (catalog IF captions).
Real IHC data
Anti-Cytokeratin 8 KRT8 Rabbit Monoclonal Antibody
Cat # M01421-2
Real IHC data
Anti-Cytokeratin 8 KRT8 Antibody ® (monoclonal, 3G9)
Cat # M01421-3
Real IHC data
Anti-Cytokeratin 8/KRT8 Antibody ®
Cat # PA1240
Real IHC data
Anti-Cytokeratin 8 Rabbit Monoclonal Antibody
Cat # M01421-6
M01421-2 shows KRT8 staining in human lung cancer paraffin sections (M01421-2 IHC caption), and M01421-3 shows it in human rectal cancer paraffin sections (M01421-3 IHC caption). M01421-6 has IHC images from human colon carcinoma and mouse and rat stomach (M01421-6 IHC captions); PA1240’s image caption identifies the stained target as ITGB3, so it does not document KRT8 staining (PA1240 IHC caption).
Which to pick: For tissue IHC, M01421-2 has a rabbit monoclonal antibody with an illustrated human paraffin section at 1:50 after EDTA pH 8.0 retrieval; the caption does not report the fixative (M01421-2 catalog entry and IHC caption). For IF/ICC, M01421-3 lists both applications and has IF images from human paraffin sections and cultured cells (M01421-3 applications and IF captions). For IHC across human, mouse and rat, M01421-6 lists all three species and has an IHC image for each, though its captions do not report fixation or retrieval conditions (M01421-6 catalog entry and IHC captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P05787 (K2C8_HUMAN, Keratin, type II cytoskeletal 8).
- Human Protein Atlas. KRT8 tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. KRT8 subcellular location (ICC-IF): Localized to the intermediate filaments..
- Human Protein Atlas. KRT8 antibody validation summary (3 antibodies).
- Cytokeratin-8 in Anaplastic Thyroid Carcinoma: More Than a Simple Structural Cytoskeletal Protein. International journal of molecular sciences 2018 — PMC5855799.
- Merkel Cell Polyomavirus T Antigens Induce Merkel Cell-Like Differentiation in GLI1-Expressing Epithelial Cells. Cancers 2020 — PMC7409360.
- An Airway Protection Program Revealed by Sweeping Genetic Control of Vagal Afferents. Cell 2020 — PMC7197391.
- High KRT8 Expression Independently Predicts Poor Prognosis for Lung Adenocarcinoma Patients. Genes 2019 — PMC6360019.
- PubMed PMID:1691124 — UniProt-cited evidence.
- PubMed PMID:1692965 — UniProt-cited evidence.
- PubMed PMID:1705144 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for KRT8 (Keratin, type II cytoskeletal 8). Expected localisation Cytoplasmic and membranous staining (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet M01421-2). Validated IHC antibody: M01421-2 at 1:50 (the product's own IHC validation image is shown). Controls (HPA): positive Appendix (Endocrine cells); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human lung cancer tissue; fixative not specified (datasheet M01421-2); 2. Fixation: Image fixative and duration unreported (datasheet M01421-2); verify before use.; 3. Sectioning: 4–5 µm sections on charged slides (standard); 4. Deparaffinisation: Xylene, graded ethanol series to water (standard); 5. Antigen retrieval: Heat retrieval: EDTA pH 8.0 (datasheet M01421-2); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet M01421-2); 8. Primary antibody: Rabbit monoclonal (clone CIG-11) anti-KRT8, 1:50 (datasheet M01421-2); 9. Primary incubation: Overnight at 4 °C (datasheet M01421-2). Watch for: Fixation: Keep fixation consistent across sections. (standard IHC practice; not target-specific); Caveat: Esophageal squamous cells may lack staining (HPA tissue IHC); Isoform / epitope: 2 isoforms; epitope impact is undetermined (UniProt); Regulation: No stimulus-dependent regulator is specified (UniProt). Evidence: UniProt P05787, HPA tissue IHC · Enhanced, HPA ICC-IF · intermediate filaments., Datasheet M01421-2, PMC5855799. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/KRT8/immunohistochemistry-ihc-guide.