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BLM / RecQ-like DNA helicase BLM · IHC design guide
Design Immunohistochemistry for BLM
Plan paraffin-section BLM IHC using the catalog antibody’s 1:100–1:300 dilution range (datasheet: IHC). Assess nuclear staining while allowing for variation across tissues (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
BLM 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 | Nuclear staining in most tissues (HPA tissue IHC) | |
| Staining pattern | Variable nuclear staining across most tissues (HPA tissue IHC) | |
| Antigen retrieval | Tris-EDTA pH 9.0 HIER, 95–98 °C, 20 min (rule: nuclear antigen) | |
| Positive control | Adrenal gland+4 more · see all | |
| Negative control | None in HPA (detected in all 44 tissues); use no-primary + isotype controls |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation consistent across sections (standard IHC practice; not target-specific) | |
| Caveat | Staining has low consistency with RNA expression (HPA tissue IHC) | |
| Regulation | HU/CPT redistribute BLM to nuclear foci (UniProt) | |
| Isoform / epitope | One 1–1417 chain; no isoforms annotated (UniProt) |
Section 1
Recommended BLM IHC & IF Protocols
The catalog antibody’s IHC-P protocol is accompanied by published BLM IHC protocols for colorectal carcinoma and hepatocellular carcinoma (PMC4453952; PMC7302385).
| Sample | Paraffin-embedded human lymph node tissue; fixative not specified (datasheet A00724) |
| Fixation | Image fixative and duration unreported (datasheet A00724); 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 Tris-EDTA buffer, pH 9.0, 20 min at 95–98 °C (standard rule: nuclear 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-BLM, 1:100-1:300 (datasheet A00724) |
| 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 | BLM-positive staining in glandular cells of adrenal gland (HPA tissue IHC: High). HPA tissue profile: Nuclear expression at varying levels in most tissues. No signal in the no-primary control. |
💡Decision noteStart with Tris-EDTA pH 9.0 HIER at 95–98 °C for 20 min (page retrieval rule: nuclear antigen); the colorectal study used pH 6 HIER (PMC4453952).
Section 2
What Is the Expected BLM Staining Pattern?
BLM should appear mainly in nuclei, with varying staining levels across most tissues (UniProt P54132; HPA tissue IHC). HPA reports high staining in several glandular and epithelial cell populations, including adrenal glandular cells and bronchial respiratory epithelial cells (HPA tissue IHC). Its tissue IHC assessment is Approved, but antibody staining has low consistency with RNA expression data (HPA tissue IHC). BLM has no transmembrane segment (UniProt P54132 topology).
| Distinct nuclear chromogen in adrenal glandular cells or bronchial respiratory epithelial cells, with less staining in neighboring cells (HPA tissue IHC). | This matches the reported compartment and two high-staining cell populations (UniProt P54132; HPA tissue IHC). Judge the result by cell identity and nuclear localization together; HPA reports varying nuclear expression across most tissues, so uniform intensity is not required (HPA tissue IHC). |
| Predominantly membrane, extracellular, or strong cytoplasmic staining with little nuclear signal (UniProt P54132; HPA tissue IHC). | That distribution conflicts with the expected nuclear IHC pattern and BLM's lack of a transmembrane segment (UniProt P54132 topology; HPA tissue IHC). Check section morphology, detection controls, and antibody conditions before scoring it as BLM (standard IHC practice). HPA's additional cytosolic ICC-IF location is uncertain and does not establish a cytoplasmic IHC pattern (HPA subcellular). |
| Strong chromogen in an unexpected cell population while nuclei of an HPA high-staining population remain weak (HPA tissue IHC). | Consider cross-reactivity or endogenous detection activity, especially if staining also appears in the reagent control (standard IHC practice). HPA lists specific high-staining cell populations but rates tissue IHC only Approved, with low staining–RNA consistency; a discordant population needs independent review rather than automatic rejection (HPA tissue IHC). |
| Diffuse color covers nuclei, cytoplasm, and tissue spaces, obscuring individual cells (standard IHC practice). | This cannot reliably establish BLM's reported nuclear pattern (UniProt P54132; HPA tissue IHC). Excess antibody or detection reagent, incomplete blocking, or inadequate washing can raise background; compare a control section and optimize one workflow variable at a time (standard IHC practice). |
| No nuclear signal in adrenal glandular cells or bronchial respiratory epithelial cells (HPA tissue IHC). | Those populations are reported as high-staining, so an absent result warrants a technical check, including section quality, antibody application, detection, and a suitable positive control (HPA tissue IHC; standard IHC practice). Their HPA classification is a reference pattern, not proof that every specimen or antibody run must be positive (HPA tissue IHC). |
💡Expected BLM appearanceCall positive a cell-resolved nuclear chromogen signal in an HPA high-staining population, such as adrenal glandular cells, allowing variable intensity; dominant membrane or diffuse nonnuclear color is suspect (UniProt P54132; HPA tissue IHC; standard IHC practice).
| Compartment and topology | BLM is nuclear and has no transmembrane segment (UniProt P54132). HPA describes nuclear IHC expression at varying levels in most tissues; membrane staining alone is therefore a poor match (HPA tissue IHC; UniProt P54132 topology). |
| Tissue and cell selection | HPA records high staining in adrenal, appendix, breast, and cervical glandular cells and bronchial respiratory epithelial cells (HPA tissue IHC). It records low staining in liver cholangiocytes and bone marrow hematopoietic cells; those are weaker checks for a missing signal (HPA tissue IHC). |
| Strength of HPA evidence | Tissue IHC is Approved, with low consistency between antibody staining and RNA expression (HPA tissue IHC). The listed antibody HPA005689 is IHC Approved and ICC Supported; neither status makes a single unexpected staining pattern conclusive (HPA antibodies; HPA tissue IHC). |
| ICC-IF comparison | HPA supports nucleoplasmic localization by ICC-IF and marks additional cytosolic localization uncertain (HPA subcellular). Use that observation as compartment context, not as proof that cytoplasmic chromogen in paraffin tissue is specific (HPA subcellular; standard IHC practice). |
| Antigen retrieval | Target-specific fixation effects are not established by the supplied assay evidence. Verify with a matched IHC source before attributing a result to fixation. |
| Situation | Likely cause | Next action |
|---|---|---|
| A high-staining reference population has no detectable nuclei (HPA tissue IHC). | The run may have failed at antibody incubation, retrieval, or chromogen detection (standard IHC practice). | Target-specific fixation effects are not established by the supplied assay evidence. Verify with a matched IHC source before attributing a result to fixation. |
| Color is strongest at cell borders, with little nuclear staining (UniProt P54132; HPA tissue IHC). | The pattern conflicts with nuclear BLM and its lack of a transmembrane segment (UniProt P54132 topology). | Review morphology and a reagent control; adjust antibody or detection conditions if background persists, then reassess nuclear staining (standard IHC practice). |
| Most tissue compartments show diffuse brown haze (standard IHC practice). | Excess detection activity, insufficient blocking, or inadequate washing may obscure a specific nuclear pattern (standard IHC practice; HPA tissue IHC). | Compare the reagent control, strengthen appropriate blocking or washes, and titrate the IHC-validated antibody within its instructions (standard IHC practice). |
| Unexpected cells stain more strongly than the selected HPA high-staining population (HPA tissue IHC). | Cross-reactivity or endogenous detection activity is possible; HPA also reports low staining–RNA consistency (standard IHC practice; HPA tissue IHC). | Check cell identity and reagent controls, then compare another supported positive population before assigning specificity (HPA tissue IHC; standard IHC practice). |
| Bone marrow hematopoietic cells give weak signal despite tissue-enhanced RNA classification (HPA tissue IHC). | HPA lists these cells as low by protein staining; RNA specificity does not set their expected IHC intensity (HPA tissue IHC). | Use an HPA high-staining cell population to assess the run and report marrow staining separately from the RNA classification (HPA tissue IHC; standard IHC practice). |
| Cytoplasmic color is interpreted as a positive result because ICC-IF shows some cytosol (HPA subcellular). | HPA calls the cytosolic ICC-IF location uncertain, while tissue IHC is described as nuclear (HPA subcellular; HPA tissue IHC). | Score the tissue result by resolved nuclear staining and investigate cytoplasmic-only color with controls before reporting it as BLM (UniProt P54132; HPA tissue IHC; standard IHC practice). |
Experiment evidence
IHC & IF images showing BLM staining
A00724 · IHCImmunohistochemistry analysis of paraffin-embedded human lymph node tissue, using Bloom Syndrome Antibody. The picture on the right is block
A00724 · IFImmunofluorescence analysis of A549 cells, using Bloom Syndrome Antibody. The picture on the right is blocked with the synthesized peptide.
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000197299-BLM/tissue/cerebral+cortex#imid_2321952
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000197299-BLM/tissue/colon#imid_2309294
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000197299-BLM/tissue/liver#imid_2309287
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000197299-BLM/tissue/kidney#imid_2309280
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA005689; green = BLM, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA005689; green = BLM, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for BLM IHC & IF
🧪Run appendix first: its glandular cells show high BLM staining (HPA: High in appendix glandular cells). HPA detects BLM in all 44 scored tissues, so there is no supported negative tissue; use no-primary and isotype controls, and treat cells lacking specific nuclear staining on the positive slide as background rather than assigning them a negative cell identity (HPA: no negative tissue rows; UniProt P54132: nucleus).
Positive control tissue: Adrenal gland (Glandular cells, HPA High)
Negative control tissue: None in HPA: BLM is detected in all 44 scored tissues. Use a no-primary (secondary-only) and an isotype control instead.
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show BLM in A-431, U-251MG, U2OS, with annotated localisation: Nucleoplasm (supported) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only slide and a species- and clonality-matched isotype control; a peptide-blocked section provides a biological specificity check (A00724 tissue-IHC caption: peptide block). For chromogenic IHC in appendix, quench endogenous peroxidase and check inflammatory regions for background (standard IHC practice).
⚠️Feasibility: A target-specific fixation window and fixation effect are unreported, and the selected paraffin-section caption does not state a fixative (A00724 tissue-IHC caption). Retrieval dependence is unreported, so optimize antigen retrieval empirically for the IHC-validated antibody (standard IHC practice). The supplied evidence does not establish that frozen sections or IF/ICC are easier; in appendix, inflammatory cells can produce peroxidase background that needs control (HPA: High in appendix glandular cells; standard IHC practice).
HPA tissue IHC evidence for BLM
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Approved — Low 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 |
|---|---|---|---|---|
| Adrenal gland | Glandular cells | High | Protein (IHC) | HPA → |
| Appendix | Glandular cells | High | Protein (IHC) | HPA → |
| Breast | Glandular cells | High | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | High | Protein (IHC) | HPA → |
| Caudate | Glial cells | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| None in HPA: BLM is detected in all 44 scored tissues. Use a no-primary (secondary-only) and an isotype control instead. | ||||
Section 3
Advanced BLM IHC Tips
Troubleshoot BLM staining in paraffin sections by checking nuclear signal, section controls, and the limits of the available antibody evidence.
How should I retrieve BLM in paraffin sections when nuclear staining is weak?
Start with Tris-EDTA at pH 9.0 for heat-induced retrieval at 95–98 °C for 20 min (page retrieval setting). Let sections cool in buffer, then compare nuclear staining with a section processed identically but without primary antibody (standard IHC practice). If staining remains weak, test a shorter or longer heating interval on serial sections while keeping detection conditions constant (standard IHC practice). Score nuclei rather than overall brown color, because BLM is nuclear and HPA reports nuclear expression at varying levels in most tissues (UniProt P54132 localization; HPA tissue IHC profile).
Could fixation explain weak or uneven BLM staining?
BLM-specific sensitivity to fixation is unknown from the supplied evidence; the A00724 tissue image identifies paraffin embedding but does not state a fixative (A00724 caption). Record the fixative, fixation duration, processing history, and section thickness before comparing cases, because those variables can affect chromogenic staining (standard IHC practice). Compare adjacent sections with the same retrieval and antibody conditions, and inspect whether staining loss follows a processing batch or a tissue boundary (standard IHC practice). Do not infer a BLM-specific fixation effect from its nuclear location, modified residues, or HPA tissue pattern (UniProt P54132 localization and modified residues; HPA tissue IHC profile).
How should I evaluate nuclear and cytoplasmic BLM staining?
Treat nuclear staining as the principal expected pattern: UniProt places BLM in the nucleus, and HPA reports nuclear expression at varying levels in most tissues (UniProt P54132 localization; HPA tissue IHC profile). HPA supports a nucleoplasmic location but labels its additional cytosolic location uncertain, so score cytoplasmic color separately (HPA subcellular). Compare the suspected signal with nuclear counterstain and a no-primary section, especially where dense chromogen makes compartment boundaries difficult to see (standard IHC practice). Discrete nuclear foci have a biological context after hydroxyurea or camptothecin treatment; do not assign that context to untreated tissue from appearance alone (UniProt P54132 localization).
What epitope issues matter when BLM staining changes between specimens?
The supplied record lists 0 isoforms and a single 1–1417 amino-acid chain, so an isoform-specific staining explanation is unsupported here (UniProt P54132 processing and isoforms). The antibody epitope is not specified in the payload; obtain its mapping before attributing variable staining to epitope exposure (supplied antibody evidence). BLM has annotated helicase ATP-binding, helicase C-terminal, and HRDC domains, plus modified residues, but these annotations do not establish antibody binding behavior in sections (UniProt P54132 domains and modified residues). Compare serial sections under controlled retrieval conditions and use the A00724 peptide-blocked image as specificity context for that exact antibody (standard IHC practice; A00724 caption).
How can IF help resolve an ambiguous chromogenic BLM pattern?
Use IF/ICC as a separate assay and verify the antibody's suitability there before interpreting fluorescent signal as BLM (standard IF practice). Multiplex BLM with a marker for the cell type being evaluated, chosen from the specimen's established identity, and include a nuclear counterstain to locate the expected nucleoplasmic signal (standard IF practice; HPA subcellular). Select a fluorophore channel after checking unstained tissue autofluorescence, and include single-color controls when assessing overlap (standard IF practice). Because BLM has no transmembrane segment and is principally nuclear, use a permeabilisation step compatible with nuclear epitope access, then optimize it empirically for the antibody (UniProt P54132 topology and localization; standard IF practice).
How can I distinguish BLM staining from chromogenic background?
Inspect a section without primary antibody alongside the stained section to identify signal from detection reagents or tissue components (standard IHC practice). Apply a peroxidase block before an HRP/DAB detection workflow, and check whether residual brown deposits track areas rich in endogenous enzyme activity (standard IHC practice). Use an appropriate protein block and titrate the antibody and detection reagents if diffuse staining obscures nuclei; no working dilution is supplied here (standard IHC practice; supplied antibody evidence). The A00724 paraffin-section image includes a peptide-blocked comparison, which supports evaluating that antibody's signal but does not establish specificity in every tissue or preparation (A00724 caption).
What is a defensible way to quantify BLM IHC? ⚠ ANSWER MARKED FOR VERIFICATION
Define the tissue compartment and eligible cell population before scoring, then measure nuclear staining because nuclear expression is the reported dominant pattern (standard IHC practice; HPA tissue IHC profile). Report the percentage of positive nuclei and, where intensity is reproducible, an H-score based on the proportions at each staining intensity (standard IHC practice). Normalize each result to the number of evaluable nuclei in the selected region, or report positive-cell density per mm² with the sampled area stated (standard IHC practice). Keep retrieval, imaging, thresholds, and exclusion rules consistent, and report cytoplasmic staining separately because its HPA localization assignment is uncertain (standard IHC practice; HPA subcellular).
When should I doubt an apparent BLM-positive result?
Give greatest weight to staining that resolves within intact nuclei in morphologically evaluable cells, consistent with BLM's nuclear location (UniProt P54132 localization; standard IHC practice). Question isolated cytoplasmic or extracellular deposits, especially because HPA describes cytosolic localization as uncertain (HPA subcellular; standard IHC practice). Exclude section edges, necrotic regions, and areas where the no-primary control reveals residual endogenous enzyme signal before assigning positivity (standard IHC practice). Check cell identity and compare with relevant control sections; HPA lists high staining in several cell populations but also notes low consistency between antibody staining and RNA expression, so its pattern alone cannot confirm a result (HPA tissue IHC profile and reliability description).
Boster reagents
Best BLM / RecQ-like DNA helicase BLM IHC Antibodies
The IHC-validated anti-BLM antibody has an image from paraffin-embedded human lymph node, and its IF image shows A549 cells (A00724 image captions). Human and mouse reactivity is listed (A00724 catalog).
Real IHC data
Anti-Bloom syndrome protein BLM Antibody
Cat # A00724
A00724 renders with an IHC image of paraffin-embedded human lymph node; the paired image shows peptide blocking (A00724 IHC image caption). Its IF image shows A549 cells with a paired peptide-blocking image, while human and mouse are listed as reactive species (A00724 IF image caption; catalog reactivity).
Which to pick: Choose A00724 for paraffin-section IHC: its IHC image uses paraffin-embedded human lymph node, and the listed dilution is 1:100–1:300 (A00724 IHC image caption; datasheet). For cell IF/ICC planning, A00724 has an IF image in A549 cells and a listed IF dilution of 1:200–1:1000; separate ICC validation is unreported (A00724 IF image caption; datasheet). A00724 also lists mouse reactivity, although its shown IHC and IF images do not establish mouse-sample performance; clonality and the IHC specimen’s fixative are unreported (A00724 catalog; IHC and IF image captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P54132 (BLM_HUMAN, RecQ-like DNA helicase BLM).
- Human Protein Atlas. BLM tissue IHC expression (reliability: Approved).
- Human Protein Atlas. BLM subcellular location (ICC-IF): Mainly localized to the nucleoplasm. In addition localized to the cytosol..
- Human Protein Atlas. BLM antibody validation summary (1 antibodies).
- Tailoring heated intraperitoneal mitomycin C for peritoneal metastases originating from colorectal carcinoma: a translational approach to improve survival. British journal of cancer 2015 — PMC4453952.
- Random-forest algorithm based biomarkers in predicting prognosis in the patients with hepatocellular carcinoma. Cancer cell international 2020 — PMC7302385.
- Sulforaphane attenuates pulmonary fibrosis by inhibiting the epithelial-mesenchymal transition. BMC pharmacology & toxicology 2018 — PMC5879815.
- Downregulation of BLM RecQ helicase inhibits proliferation, promotes the apoptosis and enhances the sensitivity of bladder cancer cells to cisplatin. Molecular medicine reports 2022 — PMC9437972.
- PubMed PMID:7585968 — UniProt-cited evidence.
- PubMed PMID:9388193 — UniProt-cited evidence.
- PubMed PMID:15489334 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for BLM (RecQ-like DNA helicase BLM). Expected localisation Nuclear staining in most tissues (HPA tissue IHC). Antigen retrieval: Tris-EDTA pH 9.0 HIER, 95–98 °C, 20 min (rule: nuclear antigen). Validated IHC antibody: A00724 at 1:100-1:300 (the product's own IHC validation image is shown). Controls (HPA): positive Adrenal gland (Glandular cells); negative None in HPA (detected in all 44 tissues); use no-primary + isotype controls. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human lymph node tissue; fixative not specified (datasheet A00724); 2. Fixation: Image fixative and duration unreported (datasheet A00724); 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 Tris-EDTA buffer, pH 9.0 , 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-BLM, 1:100-1:300 (datasheet A00724); 9. Primary incubation: Overnight at 4 °C (standard). Watch for: Fixation: Keep fixation consistent across sections (standard IHC practice; not target-specific); Caveat: Staining has low consistency with RNA expression (HPA tissue IHC); Isoform / epitope: One 1–1417 chain; no isoforms annotated (UniProt); Regulation: HU/CPT redistribute BLM to nuclear foci (UniProt). Evidence: UniProt P54132, HPA tissue IHC · Approved, HPA ICC-IF · Mainly localized to the nucleoplasm. In addition localized to the…, Datasheet A00724, PMC4453952, PMC7302385. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/BLM/immunohistochemistry-ihc-guide.