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KMO / Kynurenine 3-monooxygenase · IHC design guide
Design Immunohistochemistry for KMO
Plan chromogenic KMO IHC in paraffin sections using kidney proximal tubules as a high-staining reference (HPA tissue IHC). This guide covers cytoplasmic scoring (HPA tissue IHC), fixation consistency (standard IHC practice) and the catalog antibody’s 2–5 μg/ml range (datasheet A05469-3).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
KMO 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 in tissue (HPA tissue IHC); outer mitochondrial membrane (UniProt) | |
| Staining pattern | Cytoplasmic in proximal tubules, hepatocytes and trophoblasts (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A05469-3) | |
| Positive control | Kidney+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 paraffin-section fixation consistent (standard IHC practice; not target-specific) | |
| Caveat | Endogenous peroxidase can add liver DAB background (standard IHC practice) | |
| Regulation | No expression regulator specified (UniProt) | |
| Isoform / epitope | 3 isoforms; antibody epitope and isoform coverage are unspecified (UniProt; datasheet A05469-3) |
Section 1
Recommended KMO IHC & IF Protocols
The catalog antibody’s IHC-P protocol is paired with four published KMO IHC protocols covering mouse colon, breast cancer tissue, canine mammary tumors, and kidney sections (PMC7081011; PMC7590459; PMC6521384; PMC11148292).
| Sample | Paraffin-embedded human liver cancer tissue; fixative not specified (datasheet A05469-3) |
| Fixation | Image fixative and duration unreported (datasheet A05469-3); 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 A05469-3); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A05469-3) |
| Primary antibody | Rabbit anti-KMO, 2-5 μg/ml (datasheet A05469-3) |
| Primary incubation | Overnight at 4 °C (datasheet A05469-3) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet A05469-3) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | KMO-positive staining in proximal tubules (cell body) of kidney (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic expression in liver, kidney, placenta, endometrial glands and lymphoid tissues. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA at pH 8.0 for the catalog antibody (datasheet: A05469-3); published KMO protocols also use EDTA pH 8.0 or citrate pH 6.0 (PMC11148292; PMC7081011; PMC6521384).
Section 2
What Is the Expected KMO Staining Pattern?
KMO is assigned to the mitochondrial outer membrane, with two transmembrane segments (UniProt O15229: topology). In paraffin IHC, expect cytoplasmic staining, strongest in kidney proximal tubules and present in hepatocytes, placental trophoblastic cells, endometrial glandular cells and splenic white-pulp cells (HPA: tissue IHC). HPA rates the tissue profile Enhanced, while reporting medium consistency between antibody staining and RNA expression (HPA: reliability).
| Kidney proximal-tubule cell bodies stain strongly; hepatocytes and placental trophoblastic cells stain less intensely. | This matches HPA's High proximal-tubule and Medium hepatocyte and trophoblastic-cell IHC levels (HPA: tissue IHC). Score cell types separately: a positive kidney section establishes that staining can be detected in that run, but does not by itself establish specificity in every tissue (standard IHC practice). |
| Predominantly nuclear staining appears where cytoplasmic staining was expected. | A nuclear-dominant pattern conflicts with HPA's cytoplasmic tissue profile and UniProt's outer-membrane assignment (HPA: tissue IHC; UniProt O15229: subcellular location). Treat it as suspect; compare the positive control and detection controls before assigning it to KMO (standard IHC practice). |
| Adipocytes or adrenal glandular cells stain as prominently as kidney proximal tubules. | HPA reports KMO as Not detected in those cells but High in proximal tubules (HPA: tissue IHC). Unexpected staining warrants a specificity check; cross-reactivity or endogenous detection activity are possible explanations, not diagnoses from appearance alone (standard IHC practice). |
| Colour covers most of the section, including spaces between cells or cells expected to be unstained. | A broad deposit obscures the cell-resolved cytoplasmic profile reported by HPA (HPA: tissue IHC). Review a primary-antibody omission control, blocking and wash steps, and chromogen development to locate background from the detection workflow (standard IHC practice). |
| Kidney proximal tubules show no convincing signal. | That conflicts with HPA's High proximal-tubule result (HPA: tissue IHC), but a negative run alone cannot distinguish assay failure from sample differences. Check section quality, reagent activity and the positive control before interpreting weaker tissues (standard IHC practice). |
💡Expected KMO appearanceCall a result consistent when cytoplasmic staining is High in kidney proximal-tubule cell bodies and detectable at Medium levels in the listed hepatocytes, trophoblastic cells or endometrial glands (HPA: tissue IHC); prominent nuclear staining or equally strong adipocyte staining is suspect (HPA: tissue IHC; UniProt O15229: location).
| Compartment and topology | UniProt assigns KMO to the mitochondrial outer membrane and lists transmembrane segments at residues 385–404 and 425–445 (UniProt O15229: topology). HPA describes cytoplasmic IHC staining (HPA: tissue IHC); chromogenic cytoplasmic colour alone cannot resolve the organelle (standard IHC interpretation). |
| Tissue and cell-type selection | Kidney proximal tubules provide the strongest listed reference; hepatocytes, trophoblastic cells, endometrial glands and splenic white-pulp cells are Medium (HPA: tissue IHC). Lymph-node and tonsil non-germinal-center cells are Low (HPA: tissue IHC), so score those sites against their own expected levels. |
| Antibody evidence | HPA lists HPA031115 and HPA056942 as IHC Enhanced, while the overall tissue profile has medium agreement with RNA (HPA: antibody validation; HPA: reliability). These annotations support comparison with the reported pattern, but do not validate every unexpected compartment or cell type. |
| Isoforms and processing | UniProt lists three KMO isoforms, a chain spanning residues 1–486 and no annotated signal peptide or propeptide (UniProt O15229: isoforms and processing). The supplied sources do not map antibody epitopes to isoforms, so an isoform-specific staining claim is unsupported. |
| Antigen retrieval | Retrieval conditions can be checked against the catalog antibody's IHC-P instructions as a general paraffin-IHC workflow step (standard IHC practice). Neither supplied source reports KMO-specific fixation sensitivity or an optimal retrieval condition; do not infer either from topology or tissue staining. |
| IF/ICC: what pattern is supported? | HPA summarizes the subcellular signal as Membrane but provides no main location or ICC-IF cell-line images (HPA: subcellular). UniProt assigns the mitochondrial outer membrane (UniProt O15229: location). The supplied IF evidence does not establish an image-level staining pattern. |
| Situation | Likely cause | Next action |
|---|---|---|
| Proximal-tubule signal is absent or faint. | A failed IHC run is possible; proximal tubules are High in the HPA reference (HPA: tissue IHC). | Inspect the positive section, reagent activity and detection steps, then check retrieval against the catalog antibody's IHC-P instructions (standard IHC practice). Avoid assigning KMO-specific fixation sensitivity from this result. |
| Nuclei dominate the stain. | The distribution conflicts with cytoplasmic IHC and outer-membrane localisation (HPA: tissue IHC; UniProt O15229: location). | Compare the same run's positive and primary-antibody omission controls; review counterstain and chromogen deposits before scoring nuclear colour as target signal (standard IHC practice). |
| Adipocytes or adrenal glandular cells are strongly positive. | Those cell types are Not detected in the HPA profile (HPA: tissue IHC); nonspecific binding or detection activity is possible (standard IHC practice). | Compare them with kidney proximal tubules and an omission control; repeat with an independently validated antibody if specificity remains uncertain (HPA: antibody validation; standard IHC practice). |
| The entire section has diffuse chromogen. | Background from incomplete blocking, washing or detection chemistry is possible (standard IHC practice); it prevents assessment of HPA's cell-specific profile (HPA: tissue IHC). | Review blocking, washes and development time, and inspect a primary-antibody omission control before changing the biological interpretation (standard IHC practice). |
| Lymph node or tonsil looks weaker than kidney. | HPA reports Low non-germinal-center staining in those tissues versus High proximal-tubule staining (HPA: tissue IHC). | Score the specified cell populations and compare with a kidney positive section; do not require equal intensity across these tissues (HPA: tissue IHC; standard IHC interpretation). |
| Hepatocytes and proximal tubules appear equally intense. | The relative intensities differ from HPA's Medium hepatocyte and High proximal-tubule levels (HPA: tissue IHC); section or detection differences may contribute (standard IHC practice). | Check controls and compare cells within appropriately processed sections; record the observed intensity without treating the HPA levels as an absolute staining threshold (standard IHC practice). |
Experiment evidence
IHC & IF images showing KMO staining
A05469-3 · IHCIHC analysis of KMO using anti-KMO antibody (A05469-3). KMO was detected in a paraffin-embedded section of human liver cancer tissue. Heat m
A05469-3 · IHCIHC analysis of KMO using anti-KMO antibody (A05469-3). KMO was detected in a paraffin-embedded section of mouse kidney tissue. Heat mediate
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000117009-KMO/tissue/cerebral+cortex#imid_19195967
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000117009-KMO/tissue/colon#imid_19201626
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000117009-KMO/tissue/liver#imid_19201649
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000117009-KMO/tissue/kidney#imid_19201647
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for KMO IHC & IF
🧪Run kidney first: proximal tubule cell bodies should stain strongly (HPA: High in kidney proximal tubules). Use adipose tissue as a negative comparator (HPA: adipocytes Not detected); on the kidney slide, non-proximal cells should show only counterstain or background, although their KMO status needs empirical confirmation because the HPA row specifies only proximal tubules (HPA: High in proximal tubules).
Positive control tissue: Kidney (Proximal tubules (cell body), HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA carries no ICC-IF cell line for KMO; derive a cell-line control from the positive tissue's cell type (Proximal tubules (cell body)) and confirm it by RNA or western blot first.
Technical controls: Include no-primary (secondary-only) and concentration-matched rabbit isotype controls, plus a KMO knockout specimen if available (standard IHC practice; selected caption: rabbit anti-KMO antibody). For kidney chromogenic IHC, block endogenous peroxidase and consider endogenous biotin if using biotin-based detection (standard IHC practice).
⚠️Feasibility: A target-specific fixation window and fixation effect are unreported; the selected A05469-3 paraffin-section caption does not state its fixative (selected tissue-IHC caption). Heat retrieval in EDTA at pH 8.0 was used in that caption, but whether retrieval is required for kidney staining is unreported (selected tissue-IHC caption). Frozen sections or IF cannot be judged easier from this evidence; kidney endogenous peroxidase or biotin may complicate chromogenic interpretation (HPA: no ICC-IF cell-line images; standard IHC practice).
HPA tissue IHC evidence for KMO
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 |
|---|---|---|---|---|
| Kidney | Proximal tubules (cell body) | High | Protein (IHC) | HPA → |
| Endometrium | Glandular cells | Medium | Protein (IHC) | HPA → |
| Liver | Hepatocytes | Medium | Protein (IHC) | HPA → |
| Placenta | Trophoblastic cells | Medium | Protein (IHC) | HPA → |
| Spleen | Cells in white pulp | Medium | 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 → |
| Appendix | Glandular cells | Not detected | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Breast | Adipocytes | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced KMO IHC Tips
Use cell-type controls and matched section processing to evaluate KMO staining in paraffin sections; reserve IF for orthogonal localisation checks.
Which retrieval condition should I start with for KMO paraffin-section IHC?
Start with heat-mediated retrieval in EDTA at pH 8.0 (datasheet A05469-3). The selected paraffin-section image used that condition before staining human liver cancer tissue, so keep it fixed while first adjusting antibody exposure and detection (datasheet A05469-3). Its primary antibody was applied at 2 μg/ml overnight at 4°C (datasheet A05469-3). Run adjacent sections through identical heating and cooling cycles to judge whether weak staining reflects retrieval rather than section variation (standard IHC practice). If staining remains weak, compare a second retrieval condition on matched sections, retaining the EDTA condition as the reference (standard IHC practice).
How should I handle fixation when KMO staining varies between paraffin blocks?
KMO-specific fixation sensitivity is unknown: the selected tissue caption identifies a paraffin-embedded section but does not state its fixative (datasheet A05469-3). Record the fixative, fixation duration and processing history for each block before comparing staining (standard IHC practice). Stain matched sections in the same run with EDTA retrieval at pH 8.0 and the same antibody concentration to limit procedural variation (datasheet A05469-3; standard IHC practice). Compare signal within viable, morphologically similar cells and examine adjacent sections for tissue damage or uneven processing (standard IHC practice). Do not assign a block-to-block difference to KMO biology until those variables are assessed (standard IHC practice).
Should KMO appear diffuse in the cytoplasm or confined to mitochondria?
Interpret chromogenic KMO signal as a cell-level cytoplasmic pattern: KMO is assigned to the mitochondrial outer membrane, while tissue IHC reports cytoplasmic expression (UniProt O15229 topology; HPA: tissue profile). The annotated membrane-spanning segments are residues 385–404 and 425–445 (UniProt O15229 topology). DAB generally lacks the resolution needed to establish outer-membrane localisation from a routine tissue section (standard IHC practice). Evaluate hepatocytes or kidney proximal tubules against their morphology and a clean negative control, because these are reported KMO-positive cell populations (HPA: hepatocytes Medium; proximal tubules High). Predominantly nuclear staining warrants a specificity review rather than a mitochondrial assignment (UniProt O15229 localisation; standard IHC practice).
Can this stain distinguish KMO isoforms or indicate which epitope survived processing?
Treat isoform-specific interpretation as unproven because KMO has 3 annotated isoforms, while this payload supplies no antibody epitope map (UniProt O15229 isoforms; datasheet A05469-3). The full-length chain spans residues 1–486, with membrane-spanning segments at 385–404 and 425–445 (UniProt O15229 topology). One glycosylation site is annotated at residue 465, but its effect on this antibody’s tissue staining is not established (UniProt O15229 glycosylation; datasheet A05469-3). Ask for the immunogen or mapped epitope before inferring which isoforms the stain detects (standard antibody validation practice). Compare an independent epitope antibody or another orthogonal assay if isoform discrimination is essential (standard antibody validation practice).
How can IF help check a KMO IHC pattern without overinterpreting colocalisation?
Use IF as an orthogonal check of the chromogenic IHC cell pattern, since KMO is assigned to the mitochondrial outer membrane (UniProt O15229 localisation; standard IF practice). Multiplex KMO with a marker identifying the expected cell population, such as hepatocytes or proximal tubule cells, and include single-label controls (HPA: hepatocytes Medium; proximal tubules High; standard IF practice). Choose a fluorophore channel with low measured tissue autofluorescence, often testing a far-red channel against an unstained section first (standard IF practice). The antibody epitope’s side of the outer membrane is unspecified, so compare mild permeabilisation conditions rather than assuming access (UniProt O15229 topology; standard IF practice). Judge colocalisation at the optical resolution used, not as proof of membrane-side topology (standard IF practice).
How do I separate KMO signal from DAB background in liver or kidney?
Inspect a no-primary control and a matched stained section to identify pigment, nonspecific deposits or endogenous peroxidase signal before scoring DAB (standard IHC practice). Apply a peroxidase-blocking step as part of the chromogenic workflow and verify its effect with the no-primary control (standard IHC practice). The selected liver cancer section used 10% goat serum blocking, a peroxidase-conjugated anti-rabbit secondary and DAB detection (datasheet A05469-3). If background persists, compare matched sections while changing one variable, such as primary concentration or wash stringency (standard IHC practice). Retain morphology and expected cell distribution as checks: hepatocytes and proximal tubules have reported KMO staining (HPA: hepatocytes Medium; proximal tubules High).
What scoring method makes KMO IHC results comparable across sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and viable tissue region before measuring KMO DAB signal; keep section processing, imaging and threshold settings consistent (standard IHC quantification practice). For hepatocytes or proximal tubule cells, report the percentage positive and an intensity-weighted H-score from 0–300 (HPA: hepatocytes Medium; proximal tubules High; standard IHC quantification practice). Normalize cell counts to the total viable cells of that type, or report positive-cell density per mm² of viable tissue (standard IHC quantification practice). Exclude necrosis, folds and section edges by a prespecified rule applied to every specimen (standard IHC quantification practice). Report replicate and control results alongside scores, since the tissue reference has medium staining–RNA consistency (HPA: Enhanced reliability description).
What findings argue that apparent KMO positivity is an artefact?
A convincing stain follows viable cell morphology and the reported distribution, including proximal tubules in kidney and hepatocytes in liver (HPA: proximal tubules High; hepatocytes Medium; standard IHC practice). Predominantly nuclear signal conflicts with the mitochondrial outer-membrane assignment and calls for antibody and control review (UniProt O15229 localisation; standard IHC practice). Staining limited to tissue edges, folds or necrotic areas suggests a processing artefact when adjacent viable cells lack the pattern (standard IHC practice). DAB signal in a no-primary control points to detection background, including possible endogenous peroxidase activity (standard IHC practice). Compare a reported negative cell population, such as adipocytes, under the same run conditions before assigning unexpected staining to KMO (HPA: adipocytes Not detected; standard IHC practice).
Boster reagents
Best KMO / Kynurenine 3-monooxygenase IHC Antibodies
A05469-3 has real IHC data from paraffin sections of human liver cancer and mouse and rat kidney (catalog IHC captions). No IF/ICC data are supplied (catalog applications; image alts).
Real IHC data
Anti-KMO Antibody ®
Cat # A05469-3
A05469-3 is listed for IHC in human, mouse and rat at 2–5 μg/ml (catalog applications, reactivity and dilution). Its IHC captions document paraffin sections of human liver cancer, mouse kidney and rat kidney (catalog IHC captions).
Which to pick: For tissue IHC, choose A05469-3, a rabbit antibody with chromogenic paraffin-section data (catalog host; IHC captions). There is no IF/ICC-validated choice in this payload (catalog applications; IF image alts). A05469-3 also covers human, mouse and rat IHC (catalog reactivity; IHC captions); the captions do not report the fixative (catalog IHC captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry O15229 (KMO_HUMAN, Kynurenine 3-monooxygenase).
- Human Protein Atlas. KMO tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. KMO subcellular location (ICC-IF): Membrane.
- Human Protein Atlas. KMO antibody validation summary (2 antibodies).
- Kynurenine plays an immunosuppressive role in 2,4,6-trinitrobenzene sulfate-induced colitis in mice. World journal of gastroenterology 2020 — PMC7081011.
- Differential kynurenine pathway metabolism in highly metastatic aggressive breast cancer subtypes: beyond IDO1-induced immunosuppression. Breast cancer research : BCR 2020 — PMC7590459.
- Overexpression of Kynurenine 3-Monooxygenase Correlates with Cancer Malignancy and Predicts Poor Prognosis in Canine Mammary Gland Tumors. Journal of oncology 2019 — PMC6521384.
- Unraveling the nexus of NAD+ metabolism and diabetic kidney disease: insights from murine models and human data. Frontiers in endocrinology 2024 — PMC11148292.
- PubMed PMID:9237672 — UniProt-cited evidence.
- PubMed PMID:10672018 — UniProt-cited evidence.
- PubMed PMID:16710414 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for KMO (Kynurenine 3-monooxygenase). Expected localisation Cytoplasmic in tissue (HPA tissue IHC); outer mitochondrial membrane (UniProt). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A05469-3). Validated IHC antibody: A05469-3 at 2-5 μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Kidney (Proximal tubules (cell body)); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human liver cancer tissue; fixative not specified (datasheet A05469-3); 2. Fixation: Image fixative and duration unreported (datasheet A05469-3); 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 A05469-3); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A05469-3); 8. Primary antibody: Rabbit anti-KMO, 2-5 μg/ml (datasheet A05469-3); 9. Primary incubation: Overnight at 4 °C (datasheet A05469-3). Watch for: Fixation: Keep paraffin-section fixation consistent (standard IHC practice; not target-specific); Caveat: Endogenous peroxidase can add liver DAB background (standard IHC practice); Isoform / epitope: 3 isoforms; antibody epitope and isoform coverage are unspecified (UniProt; datasheet A05469-3); Regulation: No expression regulator specified (UniProt). Evidence: UniProt O15229, HPA tissue IHC · Enhanced, HPA ICC-IF · Membrane, Datasheet A05469-3, PMC7081011, PMC7590459. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/KMO/immunohistochemistry-ihc-guide.