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CES2 / Cocaine esterase · IHC design guide
Design Immunohistochemistry for CES2
Plan CES2 chromogenic IHC around granular cytoplasmic staining in gastrointestinal endocrine cells, hepatocytes and renal tubules (HPA tissue IHC). The catalog antibody is documented for paraffin sections at 2–5 μg/ml, with DAB detection (datasheet A02868-2).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
CES2 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 | Granular cytoplasm (HPA tissue IHC); ER lumen (UniProt) | |
| Staining pattern | Granular cytoplasm in gut endocrine cells and hepatocytes (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A02868-2) | |
| Positive control | Colon+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 paraffin sections (standard IHC practice; not target-specific) | |
| Caveat | Gut staining may concentrate in endocrine cells (HPA tissue IHC) | |
| Regulation | Intestinal enrichment; moderate liver expression (UniProt) | |
| Isoform / epitope | 4 isoforms; mature chain starts at residue 27; map the epitope (UniProt) |
Section 1
Recommended CES2 IHC & IF Protocols
The catalog antibody’s IHC-P protocol (datasheet A02868-2) is accompanied by published cholangiocarcinoma and colorectal cancer protocols (PMC6416336; PMC4200864).
| Sample | Paraffin-embedded human liver cancer tissue; fixative not specified (datasheet A02868-2) |
| Fixation | Image fixative and duration unreported (datasheet A02868-2); 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 A02868-2); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A02868-2) |
| Primary antibody | Rabbit anti-CES2, 2-5 μg/ml (datasheet A02868-2) |
| Primary incubation | Overnight at 4 °C (datasheet A02868-2) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet A02868-2) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | CES2-positive staining in endocrine cells of colon (HPA tissue IHC: High). HPA tissue profile: Granular cytoplasmic expression in several tissues including liver, renal tubules and gastrointestinal tract. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA pH 8.0 for the catalog antibody (datasheet A02868-2); the colorectal study used citrate pH 6.0 (PMC4200864).
Section 2
What Is the Expected CES2 Staining Pattern?
CES2 should give granular cytoplasmic staining in selected cells of the gastrointestinal tract, liver and renal tubules (HPA: tissue IHC profile). It resides in the endoplasmic reticulum lumen and has no transmembrane segment (UniProt O00748: subcellular location and topology). HPA rates the tissue staining profile Enhanced, reflecting high consistency between antibody staining and RNA expression data (HPA: tissue IHC reliability).
| Granular cytoplasmic staining in hepatocytes, renal tubular cells or intestinal endocrine cells. | This matches the reported tissue pattern; HPA scores staining High in hepatocytes, kidney tubular cells, and endocrine cells of the duodenum, small intestine and colon (HPA: tissue IHC). Score the relevant cells and compartment, since a High rating for a cell population does not mean every cell in that tissue must stain. |
| Predominantly nuclear or sharply outlined cell-surface staining in a known-positive tissue. | That distribution does not fit granular cytoplasmic tissue staining (HPA: tissue IHC profile) or an ER-luminal protein without a transmembrane segment (UniProt O00748: location and topology). Treat it as suspect; review morphology, detection and controls before calling it CES2. |
| Strong staining in a cell population reported as undetected, such as adipocytes in adipose tissue. | HPA reports CES2 as Not detected in those adipocytes (HPA: tissue IHC). Consider cross-reactivity or endogenous detection activity, especially if the signal also appears in a no-primary control (general IHC practice). An HPA Not detected call is a reference pattern, not proof that every specimen must be negative. |
| Uniform haze across cells and extracellular space, obscuring cytoplasmic granules. | This is difficult to reconcile with the reported granular cytoplasmic profile (HPA: tissue IHC). Broad haze can arise from background in a chromogenic workflow (general IHC practice); compare the no-primary control and reassess blocking, washes and detection before scoring cell-specific signal. |
| No signal in a section containing morphologically identifiable hepatocytes or renal tubular cells. | Both cell populations are reported High by HPA (HPA: tissue IHC). First confirm that the expected cells are present, then check the IHC-validated antibody, retrieval and detection using its validated workflow (general IHC practice). A failed positive control prevents interpretation of negative test sections. |
💡Expected CES2 appearanceCall CES2 positive when the relevant hepatocytes, renal tubular cells or intestinal endocrine cells show discernible granular cytoplasmic staining, potentially High in HPA-scored populations (HPA: tissue IHC); nuclear-only, cell-surface-only or uniform background signal is suspect against that reference pattern (HPA: tissue IHC; UniProt O00748: topology).
| Cell population and tissue selection | UniProt reports preferential intestinal expression, highest in small intestine, with moderate liver expression (UniProt O00748: tissue specificity). HPA assigns High staining to specific intestinal endocrine cells, hepatocytes and renal tubular cells (HPA: tissue IHC). Interpret a section by its constituent cells; these summaries describe different levels of sampling. |
| Topology and maturation | CES2 has an N-terminal signal peptide at residues 1–26 and a mature chain at 27–559, with no transmembrane segment (UniProt O00748: processing and topology). Its ER-luminal annotation supports an intracellular interpretation (UniProt O00748: location); the supplied record does not establish tissue-section antibody epitope coverage or shedding. |
| Isoforms and modification | Four isoforms and glycosylation sites at residues 111 and 276 are annotated (UniProt O00748: isoforms and glycosylation). These facts alone do not show which isoforms the IHC-validated antibody detects, whether modification affects its binding, or how antigen retrieval changes its signal; avoid assigning a staining difference to them without antibody-specific evidence. |
| IF/ICC localisation? | HPA reports a main Golgi location, with additional ER and cytosol signal in ICC-IF (HPA: subcellular ICC-IF). UniProt annotates ER lumen (UniProt O00748: subcellular location). These are different localisation summaries; the ICC-IF result does not redefine the granular cytoplasmic tissue IHC reference pattern (HPA: tissue IHC). |
| Situation | Likely cause | Next action |
|---|---|---|
| Known-positive tissue shows no staining. | The expected cell population may be absent from the section, or the IHC workflow may have failed (HPA: tissue IHC; general IHC practice). | Verify tissue morphology and a concurrent positive control; check the catalog antibody's IHC-P retrieval, dilution and detection instructions before interpreting a negative result (general IHC practice). |
| Signal is mainly nuclear or at cell borders. | The compartment conflicts with granular cytoplasmic tissue staining and ER-luminal topology (HPA: tissue IHC; UniProt O00748: location and topology). | Inspect a no-primary control and the detection reagents, then compare staining with the expected cytoplasmic pattern in a known-positive cell population (general IHC practice; HPA: tissue IHC). |
| Unexpected cells stain strongly. | HPA's cell-level reference may differ from the observed specimen, or the signal may reflect cross-reactivity or endogenous detection activity (HPA: tissue IHC; general IHC practice). | Confirm cell identity on the counterstained section and compare no-primary controls; treat discordant staining as unresolved until the intended cell pattern is supported (general IHC practice). |
| Diffuse chromogen obscures cell boundaries. | Nonspecific background can mask the reported granular cytoplasmic pattern (general IHC practice; HPA: tissue IHC profile). | Check the no-primary control, reagent blocking and washes, and avoid scoring a field until cell-specific signal is distinguishable from haze (general IHC practice). |
| Only a few cells stain in an intestinal section. | HPA reports High staining specifically in endocrine cells of the duodenum, small intestine and colon; its rating is cell-specific (HPA: tissue IHC). | Identify the stained cells by morphology and score their compartment and intensity. Do not require uniform staining across the whole epithelium to match that HPA observation (HPA: tissue IHC). |
| IF/ICC localisation differs from the tissue IHC call. | HPA's ICC-IF summary emphasizes Golgi and also reports ER and cytosol, while its tissue IHC summary describes granular cytoplasm (HPA: subcellular ICC-IF; HPA: tissue IHC). | Keep the readouts application-specific: use the tissue IHC pattern for this paraffin-section interpretation and assess IF/ICC localisation against its own HPA summary (HPA: tissue IHC; HPA: subcellular ICC-IF). |
Experiment evidence
IHC & IF images showing CES2 staining
A02868-2 · IHCIHC analysis of CES2 using anti-CES2 antibody (A02868-2). CES2 was detected in a paraffin-embedded section of human liver cancer tissue. Hea
A02868-2 · IFIF analysis of CES2 using anti-CES2 antibody (A02868-2). CES2 was detected in a paraffin-embedded section of human liver cancer tissue. Heat
A02868-1 · IHCCES2 antibody (Center) (Cat. #A02868-1) immunohistochemistry analysis in formalin fixed and paraffin embedded human hepatocarcinoma followed
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000172831-CES2/tissue/cerebral+cortex#imid_19564195
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000172831-CES2/tissue/colon#imid_19564113
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000172831-CES2/tissue/liver#imid_19564114
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000172831-CES2/tissue/kidney#imid_19564131
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA018897; green = CES2, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA018897; green = CES2, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for CES2 IHC & IF
🧪Run liver first; hepatocytes should stain (HPA: High in liver hepatocytes). Use adipose tissue adipocytes as the negative comparison (HPA: Not detected in adipocytes); assess non-hepatocyte cells on the liver slide as possible internal background controls without presuming they are CES2-negative.
Positive control tissue: Colon (Endocrine cells, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show CES2 in A-431, SiHa, U2OS, with annotated localisation: Golgi apparatus (approved) (HPA subcellular).
Technical controls: Include no-primary (secondary-only), a host- and clonality-matched isotype control, and CES2 knockout material processed alongside the samples (standard IHC controls; tissue-IHC caption: rabbit anti-CES2 antibody). Block endogenous peroxidase and inspect liver pigment before interpreting DAB signal (standard chromogenic IHC practice; tissue-IHC caption: liver tissue and HRP/DAB detection).
⚠️Feasibility: A target-specific fixation window and fixation effect are unreported, and the exact A02868-2 tissue-IHC caption does not state a fixative. The paraffin-section example used heat retrieval in EDTA at pH 8.0, but it does not establish that retrieval is required for every specimen (tissue-IHC caption). The supplied evidence does not establish that frozen sections or IF are easier; liver pigment and endogenous peroxidase can complicate chromogenic interpretation (standard IHC practice).
HPA tissue IHC evidence for CES2
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — High 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 |
|---|---|---|---|---|
| Colon | Endocrine cells | High | Protein (IHC) | HPA → |
| Duodenum | Endocrine cells | High | Protein (IHC) | HPA → |
| Kidney | Cells in tubules | High | Protein (IHC) | HPA → |
| Liver | Hepatocytes | High | Protein (IHC) | HPA → |
| Lung | Alveolar cells type I | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Breast | Adipocytes | 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 CES2 IHC Tips
Troubleshoot CES2 staining in paraffin sections by checking retrieval, tissue processing, cytoplasmic localisation, controls, and cell-specific scoring.
How should I optimise retrieval when CES2 staining is weak?
Start with heat-mediated antigen retrieval in EDTA at pH 8.0 for paraffin sections (datasheet A02868-2). The selected tissue image used this retrieval before incubation with 2 μg/ml primary antibody overnight at 4°C; use those conditions as the initial comparison point (caption A02868-2). Include a liver section with hepatocytes as a positive control and a no-primary section to assess nonspecific detection (HPA: high in hepatocytes; standard IHC practice). If staining remains weak, vary heating and cooling in a controlled series while keeping section thickness and detection conditions constant, and inspect tissue morphology for retrieval damage (standard IHC practice).
Could fixation explain variable CES2 staining between paraffin sections?
The selected image documents paraffin embedding but does not state the fixative, so target-specific fixation sensitivity is unknown (caption A02868-2). Record each specimen’s fixative, fixation duration, and processing conditions, and compare staining only across similarly handled sections when possible (standard IHC practice). If signal changes after processing changes, first compare matched sections using EDTA at pH 8.0 and the documented 2 μg/ml primary concentration before adjusting detection (datasheet A02868-2; caption A02868-2). Use hepatocyte-containing liver as a positive tissue control, and assess preservation of cellular morphology alongside signal intensity (HPA: high in hepatocytes; standard IHC practice).
What staining pattern should count as plausible CES2 localisation?
Look for granular cytoplasmic staining in appropriate cells rather than treating any brown deposit as CES2 signal (HPA: granular cytoplasmic tissue expression). CES2 is annotated in the endoplasmic reticulum lumen, has a cleaved 1–26 signal peptide, and lacks a transmembrane segment (UniProt O00748: localisation, processing, topology). Cell imaging also reports a main Golgi location with additional endoplasmic reticulum and cytosolic localisation, so routine chromogenic sections cannot resolve every possible organelle assignment (HPA subcellular; standard IHC practice). Compare the pattern with hepatocytes and renal tubular cells, which have high reported tissue staining, and reject diffuse extracellular or isolated nuclear colour without corroboration (HPA tissue IHC; standard IHC practice).
Can this stain distinguish CES2 isoforms or altered epitopes?
Do not interpret staining intensity as an individual CES2 isoform measurement without an isoform-specific epitope validation experiment (UniProt O00748: 4 isoforms; standard IHC practice). The supplied product caption documents tissue staining conditions but does not identify the recognized epitope or establish isoform selectivity (caption A02868-2). CES2 has a cleaved 1–26 signal peptide, glycosylation sites at 111 and 276, and a modified residue at 27; these features make epitope position relevant to interpretation but do not prove altered staining (UniProt O00748: processing and modifications). Obtain the antibody’s epitope information or use an independently validated reagent before claiming isoform-specific or modification-dependent detection (standard IHC practice).
How can I use IF to investigate an ambiguous CES2 IHC pattern?
Use IF as a separate follow-up to the chromogenic paraffin-section result, with a marker for the cell type being evaluated, such as a hepatocyte marker in liver (HPA: high in hepatocytes; standard IF practice). Choose spectrally separated fluorophores and consider a far-red channel when tissue autofluorescence obscures the CES2 channel; include single-label and no-primary controls (standard IF practice). Because CES2 is annotated in the endoplasmic reticulum lumen, intracellular epitope access may require membrane permeabilisation, but the antibody’s epitope location is not supplied (UniProt O00748: localisation; caption A02868-2; standard IF practice). Compare cellular distribution with the IHC pattern without assuming that fluorescence and DAB intensity are directly equivalent (standard IHC/IF practice).
How do I distinguish CES2 signal from chromogenic background?
Run no-primary and secondary-only controls to identify staining produced by the detection reagents, and inspect tissue edges and damaged areas separately (standard IHC practice). The selected image used a peroxidase-conjugated secondary and DAB, so an endogenous peroxidase block and careful control of chromogen development are appropriate general workflow checks (caption A02868-2; standard IHC practice). If colour appears broadly across cells, reassess blocking, washes, primary concentration, and detection time against the documented 10% goat-serum block and 2 μg/ml primary condition (caption A02868-2; standard IHC practice). Retain a positive liver section while adjusting conditions so reduced background does not conceal genuine hepatocyte staining (HPA: high in hepatocytes; standard IHC practice).
How should I score CES2 across tissue sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and region before scoring, since reported CES2 levels differ by tissue and cell type (HPA tissue IHC; standard IHC practice). For hepatocytes or another defined population, report the percentage of positive cells and an H-score combining staining intensity with the proportion at each intensity; keep thresholds fixed across the series (HPA: high in hepatocytes; standard IHC practice). If counting discrete positive cells, report density per mm² of viable tissue or of the annotated compartment, with the denominator and excluded regions stated (standard IHC practice). Normalise comparisons to comparable cell populations and viable tissue area, and include matched positive controls to detect staining-run variation (standard IHC practice).
When is a positive CES2 stain biologically convincing?
A convincing result shows cell-associated, predominantly granular cytoplasmic staining in an expected population, such as hepatocytes, rather than colour limited to tissue edges or necrotic regions (HPA tissue IHC; standard IHC practice). The endoplasmic reticulum lumen annotation and reported Golgi, endoplasmic reticulum, and cytosolic locations support an intracellular pattern, but chromogenic IHC alone cannot assign a specific organelle (UniProt O00748: localisation; HPA subcellular; standard IHC practice). Isolated nuclear or extracellular deposits, or colour persisting in no-primary controls, warrant investigation for artefact (standard IHC practice). Check endogenous peroxidase activity when using the documented peroxidase and DAB detection workflow, then compare the remaining pattern with cell-specific reference staining (caption A02868-2; HPA tissue IHC; standard IHC practice).
Boster reagents
Best CES2 / Cocaine esterase IHC Antibodies
Both anti-CES2 antibodies have human paraffin-section IHC images; A02868-2 also has a human paraffin-section IF image and lists mouse reactivity (catalog IHC/IF captions; catalog reactivity).
Real IHC data
Anti-CES2 Antibody ®
Cat # A02868-2
Real IHC data
Anti-CES2 Antibody (Center)
Cat # A02868-1
A02868-1 will render with IHC data from formalin-fixed, paraffin-embedded human hepatocarcinoma (catalog IHC caption). A02868-2 will render with IHC data from paraffin-embedded human liver cancer; its separate IF image uses the same sample type (catalog IHC/IF captions).
Which to pick: For human tissue IHC, A02868-1 is a rabbit polyclonal antibody listed for IHC-P at 1:50–1:100 in paraffin-section, paraffin-embedded hepatocarcinoma; A02868-2 is listed for IHC at 2–5 μg/ml and shown on paraffin-embedded liver cancer after EDTA retrieval at pH 8.0, with fixative unreported (catalog dilution_raw; catalog IHC captions). For IF, choose A02868-2 at the listed 5 μg/ml for human paraffin sections; ICC validation is unreported (catalog IF application/dilution/caption). For cross-species planning, A02868-2 lists human and mouse reactivity, but its IHC and IF images show human tissue only; A02868-1 lists human reactivity only (catalog reactivity; catalog IHC/IF captions). The selected A02868-2 tissue-IHC caption documents paraffin sections, but does not specify the fixative (selected-SKU IHC image A02868-2).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry O00748 (EST2_HUMAN, Cocaine esterase).
- Human Protein Atlas. CES2 tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. CES2 subcellular location (ICC-IF): Mainly localized to the Golgi apparatus. In addition localized to the endoplasmic reticulum and cytosol..
- Human Protein Atlas. CES2 antibody validation summary (2 antibodies).
- Prognostic Impact of Carboxylesterase 2 in Cholangiocarcinoma. Scientific reports 2019 — PMC6416336.
- CES2, ABCG2, TS and Topo-I primary and synchronous metastasis expression and clinical outcome in metastatic colorectal cancer patients treated with first-line FOLFIRI regimen. International journal of molecular sciences 2014 — PMC4200864.
- Efficacy and Safety of CAP7.1 as Second-Line Treatment for Advanced Biliary Tract Cancers: Data from a Randomised Phase II Study. Cancers 2020 — PMC7692271.
- Intestinal human carboxylesterase 2 (CES2) expression rescues drug metabolism and most metabolic syndrome phenotypes in global Ces2 cluster knockout mice. Acta pharmacologica Sinica 2025 — PMC11845761.
- PubMed PMID:9144407 — UniProt-cited evidence.
- PubMed PMID:9169443 — UniProt-cited evidence.
- PubMed PMID:14702039 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for CES2 (Cocaine esterase). Expected localisation Granular cytoplasm (HPA tissue IHC); ER lumen (UniProt). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A02868-2). Validated IHC antibody: A02868-2 at 2-5 μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Colon (Endocrine cells); 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 A02868-2); 2. Fixation: Image fixative and duration unreported (datasheet A02868-2); 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 A02868-2); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A02868-2); 8. Primary antibody: Rabbit anti-CES2, 2-5 μg/ml (datasheet A02868-2); 9. Primary incubation: Overnight at 4 °C (datasheet A02868-2). Watch for: Fixation: Keep fixation consistent across paraffin sections (standard IHC practice; not target-specific); Caveat: Gut staining may concentrate in endocrine cells (HPA tissue IHC); Isoform / epitope: 4 isoforms; mature chain starts at residue 27 ; map the epitope (UniProt); Regulation: Intestinal enrichment; moderate liver expression (UniProt). Evidence: UniProt O00748, HPA tissue IHC · Enhanced, HPA ICC-IF · Mainly localized to the Golgi apparatus. In addition localized to…, Datasheet A02868-2, PMC6416336, PMC4200864. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/CES2/immunohistochemistry-ihc-guide.