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CASP1 / Caspase-1 · IHC design guide
Design Immunohistochemistry for CASP1
Plan CASP1 staining in paraffin sections using glandular cells and lung macrophages as positive tissue references (HPA tissue IHC). The guide covers fixation, chromogenic detection, and interpretation of predominantly cytoplasmic staining with occasional nuclear signal (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
CASP1 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 | Predominantly cytoplasmic; sometimes nuclear (HPA tissue IHC) | |
| Staining pattern | Cytoplasmic staining in glandular cells and lung macrophages (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen) | |
| Positive control | Duodenum+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); Matched tissue-IHC evidence does not establish the fixation claim. Validate the specimen-specific method before use. (selected-SKU IHC image M00048-3) | |
| Caveat | Cleavage into p20/p10 complicates epitope interpretation (UniProt) | |
| Regulation | Inflammasome activation drives cleavage (UniProt) | |
| Isoform / epitope | Five isoforms; p20/p10 processing makes epitope position matter (UniProt) |
Section 1
Recommended CASP1 IHC & IF Protocols
Compare the catalog antibody’s IHC-P protocol with four published CASP1 tissue IHC methods (PMC9174061; PMC5503597; PMC7202523; PMC9663582).
| Sample | Tissue sections; selected-image fixative not specified (standard IHC workflow) |
| Fixation | Image fixative and duration unreported (datasheet M00048-3); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat-induced epitope retrieval in citrate buffer, pH 6.0, 20 min at 95–98 °C (standard rule: cytoplasmic / membrane antigen) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% normal serum of the secondary host, 30 min, room temperature (standard) |
| Primary antibody | Rabbit anti-CASP1, 1:200-1:1000 (datasheet M00048-3) |
| Primary incubation | Overnight at 4 °C (standard) |
| Detection | HRP-polymer secondary, DAB chromogen 5–10 min (standard) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | CASP1-positive staining in glandular cells of duodenum (HPA tissue IHC: High). HPA tissue profile: Ubiquitous cytoplasmic expression with varying intensity that in cases was combined with nuclear expression. No signal in the no-primary control. |
💡Decision noteStart with citrate pH 6.0 retrieval at 95–98 °C for 20 min (page retrieval rule), then adjust for the tissue and antibody used.
Section 2
What Is the Expected CASP1 Staining Pattern?
CASP1 staining in paraffin sections should be mainly cytoplasmic, including in lung macrophages and glandular cells of the duodenum, gallbladder, rectum and small intestine (HPA: tissue IHC). UniProt also lists cell membrane localisation, although CASP1 has no transmembrane segment (UniProt P29466: localisation and topology). Treat this as an expected pattern, not an absolute rule: HPA rates its tissue IHC evidence Approved, with medium consistency between staining and RNA expression (HPA: reliability).
| Cytoplasmic signal in lung macrophages or glandular cells of duodenum, rectum or small intestine (HPA: High). | This fits the reported cell types and compartment (HPA: tissue IHC). Score the stained cells separately from neighbouring cells; a positive tissue does not imply that every cell in it should stain. |
| Nuclear staining is prominent while cytoplasmic staining is weak or absent. | Review before calling this a correct pattern. HPA describes mainly cytoplasmic tissue staining, sometimes with nuclear staining; its ICC-IF nucleoplasmic location is uncertain (HPA: tissue IHC; HPA: subcellular). Check morphology and staining controls. |
| Strong staining appears in adipocytes or soft-tissue fibroblasts. | These cell types were not detected in the listed HPA tissue IHC observations (HPA: Adipose tissue, Breast and Soft tissue). Consider nonspecific binding or detection background; compare a known-positive cell type processed in the same run. |
| Brown colour is widespread across cells and extracellular areas, with little cellular definition. | This does not resemble HPA's predominantly cytoplasmic, cell-resolved pattern (HPA: tissue IHC). Assess background with appropriate detection controls and review the staining workflow before interpreting it as CASP1. |
| No signal appears in lung macrophages or the listed High glandular cell populations. | These are expected positive comparisons (HPA: Lung, Duodenum, Gallbladder, Rectum and Small intestine). First check that the relevant cells are present and recognisable, then assess controls and the IHC staining workflow; an absent signal alone does not establish CASP1 absence. |
💡Expected CASP1 appearanceCall positive a cell-resolved, mainly cytoplasmic chromogenic signal in lung macrophages or the listed High glandular cell populations (HPA: tissue IHC); broad extracellular colour or strong staining in HPA Not detected cell types warrants a background check (HPA: tissue IHC).
| Cell and compartment context | HPA reports ubiquitous cytoplasmic expression of varying intensity, sometimes combined with nuclear staining (HPA: tissue IHC). Compare the specific cell population and compartment, not only the overall colour of a tissue section. |
| Tissue evidence | Lung macrophages and several intestinal glandular populations are High, while adipocytes and soft-tissue fibroblasts are Not detected in the supplied observations (HPA: tissue IHC). HPA's Approved rating has medium RNA–staining consistency (HPA: reliability). |
| Processing and antibody recognition | CASP1 is a 404-aa precursor with annotated p20 and p10 chains and five isoforms (UniProt P29466: processing and isoforms). The payload gives no antibody epitope, so the staining pattern alone cannot identify which CASP1 form an antibody detects. |
| IF/ICC Q&A: Where should signal appear? | Mainly in the cytosol; HPA also reports nucleoplasm with uncertain support (HPA: subcellular). This ICC-IF observation helps interpret localisation but does not replace the tissue IHC pattern or establish a paraffin-section IF protocol. |
| Antigen retrieval | Retrieval is a general paraffin-section IHC workflow variable. Neither supplied source reports CASP1-specific fixation sensitivity or a retrieval-dependent tissue pattern; assess any retrieval change against controls without assuming a target-specific effect. |
| Situation | Likely cause | Next action |
|---|---|---|
| A listed High cell population is present but unstained. | Possible run-level staining failure or an unsuitable antibody condition; the result alone cannot distinguish these causes (HPA: High tissue IHC populations). | Confirm cell identity and section quality, then review the catalog antibody's IHC-P conditions and run controls. Interpret a negative result only after a known-positive comparison stains as expected. |
| The whole section has weak, flat colour. | Diffuse chromogenic background can obscure the cell-resolved cytoplasmic pattern reported for CASP1 (HPA: tissue IHC). | Review blocking, washing and detection controls as general IHC practice. Compare cellular staining with a control lacking the primary antibody before scoring weak positives. |
| Colour is strongest in adipocytes or soft-tissue fibroblasts. | The supplied HPA observations mark those cell types Not detected; the signal may reflect nonspecific staining or detection background (HPA: Adipose tissue, Breast and Soft tissue). | Check tissue morphology and detection controls, then compare the same run with lung macrophages or a listed High glandular population (HPA: tissue IHC). |
| Nuclei dominate the staining. | HPA allows nuclear staining in some tissue cases, but describes cytoplasm as the prevalent location; ICC-IF nucleoplasmic support is uncertain (HPA: tissue IHC; HPA: subcellular). | Document the cytoplasmic and nuclear components separately. Check staining controls and compare another reported positive cell population before assigning a nuclear-only result to CASP1. |
| An IF/ICC image disagrees with the paraffin-section slide. | The evidence describes different applications: cytosol is supported in ICC-IF, while tissue IHC is mainly cytoplasmic with occasional nuclear staining (HPA: subcellular; HPA: tissue IHC). | Judge the IHC slide against tissue cell types and its own controls. Use the ICC-IF record only as localisation context; it supplies no IF protocol for this section. |
| A retrieved section changes staining intensity or distribution. | No CASP1-specific fixation or retrieval effect is established by the supplied UniProt and HPA records. | Treat retrieval as a general IHC variable: compare matched sections with the same known-positive cells and detection controls, and report the observed change without attributing it to a documented CASP1 epitope effect. |
Experiment evidence
IHC & IF images showing CASP1 staining
M00048-3 · IHCHuman colon carcinoma was stained with anti-Caspase-1 rabbit antibody
M00048-3 · IHCHuman small intestine was stained with anti-Caspase-1 rabbit antibody
M00048 · IHCImmunohistochemical analysis of paraffin-embedded human liver, using Caspase-1 Antibody.
PA1440 · IHCAnti-Caspase-1(P20) antibody, PA1440, IHC(P) IHC(P): Human Mammary Cancer Tissue
PA1522 · IHCAnti-Caspase-1(P10) antibody, PA1522, IHC(P) IHC(P): Human Mammary Cancer Tissue
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000137752-CASP1/tissue/cerebral+cortex#imid_836768
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000137752-CASP1/tissue/colon#imid_836686
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000137752-CASP1/tissue/liver#imid_836703
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000137752-CASP1/tissue/kidney#imid_836696
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody CAB002685; green = CASP1, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody CAB002685; green = CASP1, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for CASP1 IHC & IF
🧪Run lung first and assess macrophages for staining, because HPA rates CASP1 expression in lung macrophages as High (HPA: High in lung macrophages). Use adipose tissue adipocytes as the negative comparison (HPA: Not detected in adipocytes); on the lung slide, nonmacrophage cells should provide a low-background internal comparison, though their CASP1 status is not specified in the supplied HPA row (HPA: lung macrophage row).
Positive control tissue: Duodenum (Glandular cells, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show CASP1 in A-431, U-251MG, U2OS, with annotated localisation: Cytosol (supported) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only slide and an isotype-matched IgG control appropriate to the primary antibody’s host species and clonality (standard IHC practice). Add a CASP1 knockout specimen, or a peptide-block control if the immunizing peptide is available, and quench endogenous peroxidase in lung sections before chromogenic detection (standard IHC practice).
⚠️Feasibility: A target-specific fixation window and the effect of fixation on CASP1 staining are unreported in the supplied evidence; the selected M00048-3 colon carcinoma caption also leaves its fixative unreported (selected-SKU tissue-IHC caption). CASP1-specific antigen retrieval requirements and whether frozen sections or IF are easier than paraffin IHC are likewise unreported; optimize retrieval with the positive and negative controls (standard IHC practice). In lung, distinguish chromogen signal from macrophage pigment during scoring (standard IHC practice).
HPA tissue IHC evidence for CASP1
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Approved — 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 |
|---|---|---|---|---|
| Duodenum | Glandular cells | High | Protein (IHC) | HPA → |
| Gallbladder | Glandular cells | High | Protein (IHC) | HPA → |
| Lung | Macrophages | High | Protein (IHC) | HPA → |
| Rectum | Glandular cells | High | Protein (IHC) | HPA → |
| Small intestine | Glandular 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 → |
| Breast | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Caudate | Glial cells | Not detected | Protein (IHC) | HPA → |
| Hippocampus | Glial cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced CASP1 IHC Tips
Troubleshoot CASP1 staining in paraffin sections by checking retrieval, cell compartment, controls, and scoring before interpreting inflammatory activity.
How should I adjust retrieval when CASP1 staining is weak?
Use citrate buffer at pH 6.0 for heat-induced retrieval at 95–98 °C for 20 min (page retrieval rule: cytoplasmic / membrane antigen). If signal remains weak, check that sections reached the intended temperature and stayed immersed for the full interval before changing conditions (standard IHC practice). Compare any revised retrieval condition on adjacent sections with the same antibody dilution and detection settings, using lung macrophages as a positive reference (HPA: High in lung macrophages). Judge improvement by clearer cellular staining without a comparable rise in diffuse background or damaged morphology (standard IHC practice).
Could fixation explain weak or uneven CASP1 staining?
CASP1-specific sensitivity to fixation is unknown from the supplied evidence, and the catalog image caption does not state its fixative (catalog caption: M00048-3). Record the specimen’s fixative and fixation duration, then compare similarly processed sections before attributing intensity differences to biology (standard IHC practice). Check whether weak regions also show poor morphology or uneven staining of an independently validated control antigen on adjacent sections (standard IHC practice). If processing varies across cases, keep those cases separate during scoring and document the variation; neither tissue expression patterns nor CASP1 topology establishes a target-specific fixation effect (HPA tissue IHC; UniProt P29466 topology).
Which cellular staining patterns are plausible for CASP1?
Prioritise cellular cytoplasmic staining: CASP1 is annotated in the cytoplasm and at the cell membrane, with no transmembrane segment (UniProt P29466 localisation and topology). Tissue IHC shows broadly cytoplasmic expression, sometimes with nuclear staining, while cell imaging supports cytosol and labels nucleoplasm uncertain (HPA tissue IHC; HPA subcellular). Compare suspected nuclear signal with the hematoxylin counterstain and with cytoplasmic signal in the same cell population before assigning a compartment (standard IHC practice). Staining confined to tissue folds, section edges, or empty spaces should prompt a morphology and background check before it is scored as CASP1 (standard IHC practice).
Can this stain distinguish CASP1 isoforms or activated caspase-1?
Do not assign a specific isoform or activation state from this stain without knowing the antibody epitope and its validation for that claim (UniProt P29466 processing and isoforms; standard IHC practice). CASP1 has 5 named isoforms and is processed from a precursor into p20 and p10 chains, so epitope position affects which molecular forms could be recognized (UniProt P29466). An epitope in the CARD region, residues 1–91, would have different implications from one in the p20 or p10 region (UniProt P29466 domains and processing). Map the catalog antibody’s stated epitope against those regions and report staining as CASP1 immunoreactivity unless form-specific evidence is available (standard IHC practice).
How can IF help check which cells contain CASP1?
For a separate IF assay, multiplex CASP1 with a macrophage marker when examining lung, where macrophages show high tissue staining (HPA: High in lung macrophages; standard IF practice). Choose spectrally separated fluorophores and place the weaker signal in a channel with less tissue autofluorescence, checking unstained sections first (standard IF practice). CASP1 is mainly cytosolic and has no transmembrane segment, so permeabilise fixed cells or sections when the antibody must reach an intracellular epitope (HPA subcellular; UniProt P29466 topology; standard IF practice). Include single-label controls to assess channel bleed-through, and interpret colocalisation within intact cells rather than from overlapping fluorescence in crowded tissue (standard IF practice).
What should I check when chromogenic CASP1 staining is diffuse?
Run a no-primary control and inspect whether color remains in areas that also stain in the CASP1 section (standard IHC practice). For peroxidase-based chromogenic detection, check the endogenous peroxidase block and shorten substrate development if the no-primary section develops color (standard IHC practice). Reassess primary antibody dilution and blocking on adjacent sections while holding retrieval and detection settings constant, so the source of background is identifiable (standard IHC practice). Compare residual staining with intact cytoplasmic cell profiles: CASP1 is mainly cytosolic, whereas broad color over folds, debris, or empty spaces does not establish cellular localisation (HPA subcellular; standard IHC practice).
How should I score CASP1 across heterogeneous tissue sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell compartment and population before scoring, since tissue IHC reports varying cytoplasmic intensity and occasional nuclear staining (HPA tissue IHC). For each prespecified region, report the percentage of positive cells and an intensity-based H-score, with the scoring thresholds applied consistently across sections (standard IHC practice). If counting positive cells by image analysis, report density per mm² of viable tissue or of the specified compartment, excluding necrosis and folds (standard IHC practice). Normalise comparisons to the number of evaluable cells or viable area in that same region, and document staining batch and processing differences (standard IHC practice).
How do I separate credible CASP1 staining from artefact or activation claims?
A credible positive has staining within intact cells in a plausible compartment, particularly cytoplasm, and can be checked against high-staining lung macrophages (UniProt P29466 localisation; HPA: High in lung macrophages). Question isolated nuclear-only staining because nucleoplasm is an uncertain additional location in cell imaging, despite occasional nuclear staining in tissue IHC (HPA subcellular; HPA tissue IHC). Exclude edge effects, necrotic areas, and color also present in a no-primary control; the latter can reveal endogenous detection signal (standard IHC practice). Finally, CASP1 immunoreactivity alone does not establish inflammasome activation or cleavage of IL1B, IL18, or GSDMD (UniProt P29466 function and processing).
Boster reagents
Best CASP1 / Caspase-1 IHC Antibodies
Four anti-CASP1 antibodies have human tissue IHC images (catalog image captions). Listed reactivity spans human, mouse and rat; only M00048-3 lists IF, with no IF image supplied (catalog reactivity, applications and images).
Real IHC data
Anti-Caspase-1 Rabbit Monoclonal Antibody
Cat # M00048-3
Real IHC data
Anti-Caspase-1 CASP1 Rabbit Monoclonal Antibody
Cat # M00048
Real IHC data
Anti-Caspase-1(P20)/CASP1 Antibody ®
Cat # PA1440
Real IHC data
Anti-Caspase-1(P10)/CASP1 Antibody ®
Cat # PA1522
M00048-3 has a human colon carcinoma IHC image, and M00048 has a paraffin-embedded human liver IHC image (respective IHC image captions). PA1440 and PA1522 each have a human mammary cancer IHC(P) image (respective IHC image captions).
Which to pick: For paraffin-section tissue IHC, choose M00048 for human liver or PA1440/PA1522 for human mammary cancer; their captions document those samples and section preparation, but do not report the fixative (respective IHC image captions). For IF/ICC, M00048-3 is the only SKU listing IF; ICC validation and an IF image are unreported (catalog applications and images). For cross-species work, M00048-3 is a rabbit monoclonal listing human, mouse and rat reactivity; its IHC image shows human colon carcinoma staining without reported section preparation or fixative (catalog description and reactivity; M00048-3 IHC image caption).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P29466 (CASP1_HUMAN, Caspase-1).
- Human Protein Atlas. CASP1 tissue IHC expression (reliability: Approved).
- Human Protein Atlas. CASP1 subcellular location (ICC-IF): Mainly localized to the cytosol. In addition localized to the nucleoplasm..
- Human Protein Atlas. CASP1 antibody validation summary (2 antibodies).
- Comprehensive Analysis of Prognostic Value and Immune Infiltration of NLRC4 and CASP1 in Colorectal Cancer. International journal of general medicine 2022 — PMC9174061.
- Cytochrome P450 1B1 inhibition suppresses tumorigenicity of prostate cancer via caspase-1 activation. Oncotarget 2017 — PMC5503597.
- Protective effects of autophagy and NFE2L2 on reactive oxygen species-induced pyroptosis of human nucleus pulposus cells. Aging 2020 — PMC7202523.
- Significance of elevated serum and hepatic NOD-like receptor pyrin domain containing 3 (NLRP3) in hepatitis C virus-related liver disease. Scientific reports 2022 — PMC9663582.
- PubMed PMID:1574116 — UniProt-cited evidence.
- PubMed PMID:1373520 — UniProt-cited evidence.
- PubMed PMID:7876192 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for CASP1 (Caspase-1). Expected localisation Predominantly cytoplasmic; sometimes nuclear (HPA tissue IHC). Antigen retrieval: Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen). Validated IHC antibody: M00048-3 at 1:200-1:1000 (the product's own IHC validation image is shown). Controls (HPA): positive Duodenum (Glandular cells); negative Adipose tissue. IHC workflow; specimen preparation unspecified. Protocol steps: 1. Sample: Tissue sections; selected-image fixative not specified (standard IHC workflow); 2. Fixation: Image fixative and duration unreported (datasheet M00048-3); 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-induced epitope retrieval in citrate buffer, pH 6.0 , 20 min at 95–98 °C…; 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% normal serum of the secondary host, 30 min , room temperature (standard); 8. Primary antibody: Rabbit anti-CASP1, 1:200-1:1000 (datasheet M00048-3); 9. Primary incubation: Overnight at 4 °C (standard). Watch for: Fixation: Keep fixation consistent across sections (standard IHC practice; not target-specific); Matched tissue-IHC evidence does not establish the fixation claim. Validate the specimen-specific method before use. (selected-SKU IHC image M00048-3); Caveat: Cleavage into p20/p10 complicates epitope interpretation (UniProt); Isoform / epitope: Five isoforms; p20/p10 processing makes epitope position matter (UniProt); Regulation: Inflammasome activation drives cleavage (UniProt). Evidence: UniProt P29466, HPA tissue IHC · Approved, HPA ICC-IF · Mainly localized to the cytosol. In addition localized to the…, Datasheet M00048-3, PMC9174061, PMC5503597. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/CASP1/immunohistochemistry-ihc-guide.