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APOC3 / Apolipoprotein C-III · IHC design guide
Design Immunohistochemistry for APOC3
Plan chromogenic APOC3 IHC on paraffin sections using enterocytes, Paneth cells and hepatocytes as reported positive populations (HPA tissue IHC). Interpret plasma positivity and extracellular deposits in light of APOC3 secretion (HPA tissue IHC; UniProt).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
APOC3 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 | Plasma and extracellular deposits (HPA tissue IHC) | |
| Staining pattern | Enterocytes, Paneth cells and hepatocytes; extracellular deposits (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet M01416) | |
| Positive control | Duodenum+2 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 paraffin sections (standard IHC practice; not target-specific) | |
| Caveat | Secreted APOC3 may stain beyond its source cells (UniProt; HPA tissue IHC) | |
| Regulation | No specific expression regulator reported (UniProt) | |
| Isoform / epitope | No isoforms; map epitopes to mature chain aa 21–99 (UniProt) |
Section 1
Recommended APOC3 IHC & IF Protocols
The catalog antibody uses EDTA pH 8.0 heat retrieval (datasheet M01416). The four published APOC3 IHC examples below provide tissue-specific comparisons (PMC13113833; PMC10493025; PMC11383354; PMC13080510).
| Sample | Paraffin-embedded human melanoma tissue; fixative not specified (datasheet M01416) |
| Fixation | Image fixative and duration unreported (datasheet M01416); 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 M01416); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet M01416) |
| Primary antibody | Rabbit monoclonal (clone 17A47) anti-APOC3, 1:50-1:200 (datasheet M01416) |
| Primary incubation | Overnight at 4 °C (datasheet M01416) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet M01416) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | APOC3-positive staining in enterocytes of duodenum (HPA tissue IHC: High). HPA tissue profile: Plasma positivity and extracellular deposits. Expressed in hepatocytes and small intestines. No signal in the no-primary control. |
💡Decision noteStart with EDTA pH 8.0 retrieval for the catalog antibody (datasheet M01416). Citrate pH 6.0 microwave retrieval was used for ovarian sections (PMC10493025).
Section 2
What Is the Expected APOC3 Staining Pattern?
APOC3 is a secreted protein with no transmembrane segment (UniProt P02656: subcellular location and topology). In paraffin IHC, expect plasma positivity and extracellular deposits alongside staining in duodenal enterocytes and small intestinal Paneth cells at high levels, and hepatocytes at medium levels (HPA tissue IHC). HPA rates the tissue pattern Supported, while noting that secreted protein can appear in different places from its RNA source (HPA tissue IHC).
| Extracellular or plasma staining accompanies signal in enterocytes, Paneth cells or hepatocytes. | This fits the reported tissue pattern (HPA tissue IHC). Compare cells within each tissue: enterocytes and Paneth cells are High, whereas hepatocytes are Medium (HPA tissue IHC). Extracellular signal can reflect secreted APOC3, so score cellular and deposited staining separately (UniProt P02656: Secreted; HPA tissue IHC: extracellular deposits). |
| The dominant IHC signal is confined to nuclei, with little expected cellular or extracellular staining. | Treat this as discordant with the tissue IHC profile and check specificity and detection controls before calling it APOC3 (HPA tissue IHC: plasma positivity and extracellular deposits). HPA separately reports approved nucleoplasmic ICC-IF localisation; that result should not be used alone to define the paraffin IHC pattern (HPA subcellular ICC-IF; HPA tissue IHC). |
| Strong staining appears mainly in adipocytes or another HPA negative cell population. | Adipocytes in adipose tissue are Not detected in the supplied tissue profile (HPA tissue IHC). Review morphology, antibody specificity and endogenous chromogen activity; staining outside the reported pattern raises concern for cross-reactivity or detection artefact, but does not establish either cause by itself (HPA tissue IHC; general IHC practice). |
| Colour spreads across tissue, empty spaces and the negative control without a clear cell pattern. | This is diffuse background rather than interpretable localisation (general IHC practice). Compare the control slide and inspect blocking, washes and detection chemistry before scoring APOC3; the reported pattern includes particular cells plus plasma and extracellular deposits, so extracellular colour alone needs morphological context (HPA tissue IHC). |
| A known positive tissue shows no convincing signal. | Use duodenum, small intestine or liver as a reference, recognising their reported High, High and Medium cellular levels, respectively (HPA tissue IHC). Check tissue integrity, retrieval and detection with appropriate controls before interpreting an absent APOC3 result; no target-specific fixation sensitivity or retrieval condition is supplied here (general IHC practice; supplied HPA and UniProt records). |
💡Expected APOC3 appearanceA credible positive slide shows plasma or extracellular signal with High enterocyte or Paneth cell staining, or Medium hepatocyte staining (HPA tissue IHC); dominant nuclear-only colour or strong signal in HPA negative adipocytes warrants review (HPA tissue IHC; HPA subcellular ICC-IF).
| Secretion and tissue distribution | APOC3 is secreted and participates in circulating VLDL and HDL (UniProt P02656: location and function). Plasma positivity and extracellular deposits can therefore accompany staining in producing cells; do not equate deposit intensity with local synthesis (HPA tissue IHC: profile and RNA/protein caveat). |
| Processing and topology | The precursor has a signal sequence at residues 1–20 and a chain at 21–99, with no transmembrane segment (UniProt P02656: processing and topology). Interpret the target as a secreted protein; epitope location and the catalog antibody’s recognition of processed material are not provided (UniProt P02656: processing; supplied antibody record). |
| Glycosylation | UniProt annotates one glycosylation site at residue 94 (UniProt P02656: glycosylation). Its effect on this antibody’s IHC staining is unreported; do not use that annotation to explain a weak or absent slide without antibody-specific evidence (supplied UniProt and HPA records). |
| Antibody validation and controls | The supplied antibody record lists HPA073918 as IHC Supported; HPA065365 has ICC Approved status but no IHC status (HPA antibodies). Choose an IHC-validated antibody for paraffin sections and interpret it against the reported positive and negative cell populations (HPA antibodies; HPA tissue IHC). |
| IF/ICC Q: Should nuclear IF define the IHC result? | A: HPA reports mainly nucleoplasmic ICC-IF localisation, with additional nucleolar and cell-junction signal (HPA subcellular ICC-IF). That is a separate assay observation; assess paraffin IHC against its tissue profile and controls (HPA tissue IHC; general IHC practice). |
| Situation | Likely cause | Next action |
|---|---|---|
| No signal in duodenal enterocytes or small intestinal Paneth cells. | These cells are High in the HPA tissue profile, so a failed positive control or weak detection is possible (HPA tissue IHC; general IHC practice). | Check section quality and control staining, then verify the antibody’s IHC use, retrieval and detection steps against its own instructions (general IHC practice; HPA antibodies: IHC Supported for HPA073918). |
| Liver looks weaker than the intestinal positive control. | Hepatocytes are Medium, while enterocytes and Paneth cells are High in the supplied profile (HPA tissue IHC). | Score each tissue against its own expected level and include an intestinal positive control if available; avoid requiring equal intensity across tissues (HPA tissue IHC; general IHC practice). |
| Signal is present only in plasma or extracellular material. | This can match a secreted protein, but it does not demonstrate staining in the reported positive cells (UniProt P02656: Secreted; HPA tissue IHC). | Record deposits separately and inspect enterocytes, Paneth cells or hepatocytes for cellular signal; compare a negative control for nonspecific colour (HPA tissue IHC; general IHC practice). |
| Strong colour appears in HPA negative adipocytes. | Adipocytes in adipose tissue are Not detected in the supplied profile; cross-reactivity or endogenous detection activity is possible (HPA tissue IHC; general IHC practice). | Compare an appropriate negative control, check endogenous activity and review tissue morphology before assigning the colour to APOC3 (general IHC practice). |
| Nuclear staining dominates the paraffin section. | This conflicts with the supplied tissue IHC profile, although nucleoplasmic localisation is reported separately for ICC-IF (HPA tissue IHC; HPA subcellular ICC-IF). | Check specificity and detection controls, then report the IHC discrepancy rather than treating the ICC-IF image as IHC validation (general IHC practice; HPA antibodies: separate IHC and ICC statuses). |
| Diffuse chromogen obscures cells and extracellular deposits. | Excess detection signal, incomplete washing or endogenous activity can create background in chromogenic IHC (general IHC practice). | Review the negative control and optimise blocking, washes and detection according to the assay instructions; rescore only when cellular and extracellular compartments are distinguishable (general IHC practice). |
Experiment evidence
IHC & IF images showing APOC3 staining
M01416 · IHCIHC analysis of APOC3 using anti-APOC3 antibody (M01416). APOC3 was detected in a paraffin-embedded section of human melanoma tissue. Heat m
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000110245-APOC3/tissue/cerebral+cortex#imid_20814052
HPA · Small intestineHuman Protein Atlas IHC, Small intestine. Source: https://www.proteinatlas.org/ENSG00000110245-APOC3/tissue/small+intestine#imid_20813937
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000110245-APOC3/tissue/colon#imid_20813962
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000110245-APOC3/tissue/liver#imid_20813979
HPA · ICC-IF CACO-2Human Protein Atlas immunofluorescence, CACO-2, antibody HPA065365; green = APOC3, blue = nucleus, red = microtubules.
HPA · ICC-IF CACO-2Human Protein Atlas immunofluorescence, CACO-2, antibody HPA065365; green = APOC3, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for APOC3 IHC & IF
🧪Run duodenum first and expect enterocytes to stain (HPA: High in duodenal enterocytes). Use adipose tissue as the negative tissue and expect adipocytes to lack detectable staining (HPA: Not detected in adipocytes); on the duodenum slide, treat unstained non-enterocyte cells as a background reference, without assigning a specific cell type as definitively negative (HPA: High in enterocytes only).
Positive control tissue: Duodenum (Enterocytes, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show APOC3 in CACO-2, Hep-G2, U2OS, with annotated localisation: Nucleoplasm (approved) (HPA subcellular).
Technical controls: Include no-primary (secondary-only) and host- and clonality-matched isotype controls; the caption identifies a rabbit primary antibody but does not state its clonality (caption: rabbit anti-APOC3 antibody M01416). Use an APOC3 knockout specimen as a biological negative if available, and quench endogenous peroxidase in the duodenum section before interpreting HRP–DAB staining (standard IHC practice; caption: HRP–DAB detection).
⚠️Feasibility: No target-specific fixation window or fixation effect is reported, and the selected M01416 paraffin-section caption does not report a fixative (caption: fixative not stated). Paraffin IHC is the documented starting workflow, with heat-mediated EDTA retrieval at pH 8.0; the evidence does not establish that frozen sections or IF/ICC are easier, or that retrieval is strictly required (caption: EDTA retrieval in a paraffin section). Interpret any luminal or extracellular signal cautiously because APOC3 is secreted (UniProt P02656: Secreted).
HPA tissue IHC evidence for APOC3
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Supported — No tissue staining or RNA expression data available for comparison. Secreted protein, tissue location of RNA and protein is expected to differ.). 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 |
|---|---|---|---|---|
| Duodenum | Enterocytes | High | Protein (IHC) | HPA → |
| Small intestine | Paneth cells | High | Protein (IHC) | HPA → |
| Liver | Hepatocytes | 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 | Endocrine 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 APOC3 IHC Tips
Troubleshoot chromogenic APOC3 IHC in paraffin sections using the catalog antibody’s documented workflow, with IF considerations kept separate.
Which retrieval conditions should I try first for APOC3 in paraffin sections?
Start with heat-mediated antigen retrieval in EDTA at pH 8.0 (datasheet M01416). The selected APOC3 image used that retrieval before staining a paraffin-embedded human melanoma section with the catalog antibody (caption M01416). If staining is weak, check that heating and cooling were consistent across sections, then compare a second retrieval condition on matched sections as a fallback (standard IHC practice). Keep antibody incubation at the documented 1:50 overnight at 4°C during that comparison, so retrieval is the main variable (caption M01416; standard IHC practice).
Can fixation explain weak or uneven APOC3 staining?
Target-specific APOC3 sensitivity to fixation is unknown from the supplied evidence; the selected paraffin-section caption does not report a fixative (caption M01416). Record each specimen’s fixation method and duration, and compare similarly processed sections before assigning weak staining to APOC3 abundance (standard IHC practice). If staining varies within a batch, review section adhesion, processing history, retrieval consistency, and reagent coverage while holding the documented EDTA pH 8.0 retrieval constant (datasheet M01416; standard IHC practice). The HPA tissue pattern and APOC3 topology cannot establish how a particular fixative affects this antibody’s epitope (HPA tissue IHC; UniProt P02656 topology).
Where should convincing APOC3 staining appear in tissue?
Expect a secreted protein to appear in extracellular material as well as near producing cells; APOC3 has no transmembrane segment (UniProt P02656 localisation and topology). HPA describes plasma positivity and extracellular deposits, with expression in hepatocytes and small intestine (HPA tissue IHC). In chromogenic sections, assess extracellular DAB separately from cell-associated staining and note whether deposits follow plausible tissue structures rather than section edges (HPA tissue IHC; standard IHC practice). The HPA subcellular page also reports nucleoplasm, nucleoli, and cell-junction signals in ICC/IF, but those observations alone do not establish the expected dominant pattern in paraffin IHC (HPA subcellular).
Could APOC3 processing or glycosylation change epitope detection?
APOC3 is a 99-aa precursor with a signal peptide at residues 1–20 and a mature chain at 21–99 (UniProt P02656 processing). UniProt lists one glycosylation site at residue 94 and no annotated isoforms, so do not assign differing IHC patterns to named isoforms (UniProt P02656 processing and glycosylation). The supplied caption does not identify this antibody’s epitope, leaving any effect of processing or glycosylation on binding unresolved (caption M01416; UniProt P02656). When comparing specimens, keep EDTA pH 8.0 retrieval and 1:50 primary dilution fixed, then evaluate whether pattern differences persist (datasheet M01416; standard IHC practice).
How should I assess APOC3 in a separate multiplex IF experiment?
For an exploratory IF assay, pair APOC3 with a hepatocyte or intestinal epithelial marker appropriate to the specimen and check whether cell-associated signal matches the expected cells (HPA tissue IHC; standard IF practice). Choose a fluorophore channel after inspecting unstained tissue autofluorescence, and include single-label controls to check bleed-through (standard IF practice). Because APOC3 is secreted and has no transmembrane segment, plan permeabilisation around whether the epitope is accessible extracellularly or requires intracellular access; the antibody’s epitope is unspecified here (UniProt P02656 topology; caption M01416; standard IF practice). The documented 1:50 incubation and EDTA pH 8.0 retrieval belong to paraffin IHC and do not establish IF conditions (caption M01416).
How can I reduce diffuse DAB background without losing APOC3 signal?
First distinguish expected extracellular APOC3 from diffuse technical stain: HPA reports plasma positivity and extracellular deposits (HPA tissue IHC). The selected image used 10% goat serum blocking, a 1:50 primary incubation overnight at 4°C, and peroxidase-based DAB detection (caption M01416). Check the no-primary control, peroxidase block, wash consistency, and DAB development time before changing primary concentration (standard IHC practice). If background persists, compare a primary dilution series on matched sections while retaining the documented retrieval, and judge the result against tissue distribution rather than demanding an entirely blank extracellular compartment (datasheet M01416; HPA tissue IHC; standard IHC practice).
What should I score when APOC3 is both cellular and extracellular? ⚠ ANSWER MARKED FOR VERIFICATION
Score cell-associated APOC3 separately from extracellular deposits because HPA reports both tissue expression and plasma or extracellular positivity (HPA tissue IHC). For a defined cell population, record the percentage of positive cells and staining intensity, or calculate an H-score using the same thresholds across slides (standard IHC practice). For deposits, measure DAB-positive area per tissue area, such as per mm², after excluding empty space, folds, and necrosis (standard IHC practice). Normalise cellular results to the number of evaluable cells in the same compartment and extracellular results to evaluable tissue area, then report those denominators and background thresholds (standard IHC practice).
How do I separate genuine APOC3 staining from artefact?
A plausible result includes hepatocyte or small-intestinal epithelial staining and potentially extracellular material, while APOC3 is secreted and lacks a transmembrane segment (HPA tissue IHC; UniProt P02656 localisation and topology). HPA reports high staining in duodenal enterocytes and small-intestinal Paneth cells, medium staining in hepatocytes, and no detected staining in adipocytes from adipose tissue (HPA tissue IHC). Treat isolated edge staining, necrotic debris, or signal reproduced in a no-primary control as reasons to investigate processing or endogenous peroxidase (standard IHC practice). Interpret unexpected nuclear-dominant DAB cautiously: HPA reports nuclear signals in ICC/IF, but the tissue-IHC profile emphasizes plasma and extracellular deposits (HPA subcellular; HPA tissue IHC).
Boster reagents
Best APOC3 / Apolipoprotein C-III IHC Antibodies
The catalog lists one human-reactive anti-APOC3 antibody with a paraffin-section IHC image; it lists no IF/ICC application or image (catalog: M01416 applications, reactivity and image captions).
Real IHC data
Anti-APOC3 Rabbit Monoclonal Antibody
Cat # M01416
M01416 is listed for human IHC and WB (catalog: M01416 applications and reactivity). Its IHC image shows a paraffin-embedded human melanoma section after EDTA retrieval at pH 8.0; the fixative is unreported (M01416 IHC caption).
Which to pick: For tissue IHC, choose M01416: it is a human-reactive rabbit monoclonal with a paraffin-section image and a listed IHC dilution of 1:50–1:200 (catalog: M01416 host, reactivity and dilution; M01416 IHC caption). There is no supported IF/ICC pick because M01416 has no listed IF/ICC application or image (catalog: M01416 applications and IF image captions). There is no supported cross-species pick because M01416 lists human reactivity only (catalog: M01416 reactivity).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P02656 (APOC3_HUMAN, Apolipoprotein C-III).
- Human Protein Atlas. APOC3 tissue IHC expression (reliability: Supported).
- Human Protein Atlas. APOC3 subcellular location (ICC-IF): Mainly localized to the nucleoplasm. In addition localized to the nucleoli and cell junctions..
- Human Protein Atlas. APOC3 antibody validation summary (2 antibodies).
- APOC3 Promotes DGAT2-Dependent Triglyceride Accumulation in Hepatocytes During Early Metabolic Dysfunction. Biomolecules 2026 — PMC13113833.
- ApoC3 is expressed in oocytes and increased expression is associated with PCOS progression. Journal of ovarian research 2023 — PMC10493025.
- Elevated apolipoprotein C3 augments diabetic kidney disease and associated atherosclerosis in type 2 diabetes. JCI insight 2024 — PMC11383354.
- Apolipoprotein C3 exacerbates vascular calcification by promoting ferroptosis via the TLR2/AMPK pathway in vascular smooth muscle cells. Redox biology 2026 — PMC13080510.
- PubMed PMID:6439535 — UniProt-cited evidence.
- PubMed PMID:6548954 — UniProt-cited evidence.
- PubMed PMID:2989400 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for APOC3 (Apolipoprotein C-III). Expected localisation Plasma and extracellular deposits (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet M01416). Validated IHC antibody: M01416 at 1:50-1:200 (the product's own IHC validation image is shown). Controls (HPA): positive Duodenum (Enterocytes); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human melanoma tissue; fixative not specified (datasheet M01416); 2. Fixation: Image fixative and duration unreported (datasheet M01416); 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 M01416); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet M01416); 8. Primary antibody: Rabbit monoclonal (clone 17A47) anti-APOC3, 1:50-1:200 (datasheet M01416); 9. Primary incubation: Overnight at 4 °C (datasheet M01416). Watch for: Fixation: Keep fixation consistent across paraffin sections (standard IHC practice; not target-specific); Caveat: Secreted APOC3 may stain beyond its source cells (UniProt; HPA tissue IHC); Isoform / epitope: No isoforms; map epitopes to mature chain aa 21–99 (UniProt); Regulation: No specific expression regulator reported (UniProt). Evidence: UniProt P02656, HPA tissue IHC · Supported, HPA ICC-IF · Mainly localized to the nucleoplasm. In addition localized to the…, Datasheet M01416, PMC13113833, PMC10493025. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/APOC3/immunohistochemistry-ihc-guide.