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FGB / Fibrinogen beta chain · IHC design guide
Design Immunohistochemistry for FGB
Plan chromogenic FGB IHC in paraffin sections around the reported plasma and extracellular staining pattern (HPA tissue IHC). This guide covers fixation, interpretation of a secreted protein, and use of an IHC-validated antibody (standard IHC practice; UniProt; datasheet A01204-1).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
FGB 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 compartments (HPA tissue IHC) | |
| Staining pattern | Strong plasma/extracellular signal; medium proximal tubule cell bodies (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A01204-1) | |
| Positive control | Kidney | |
| 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) | |
| Caveat | Extracellular signal may not identify producing cells (HPA tissue IHC) | |
| Regulation | Liver-enriched RNA; protein may differ (HPA tissue RNA) | |
| Isoform / epitope | No listed isoforms; mature chain 45–491 (UniProt) |
Section 1
Recommended FGB IHC & IF Protocols
Compare the catalog antibody’s IHC-P protocol with published FGB staining of thrombus and bioprosthetic valves (PMC12679381; PMC10401294).
| Sample | Paraffin-embedded human liver cancer tissue; fixative not specified (datasheet A01204-1) |
| Fixation | Image fixative and duration unreported (datasheet A01204-1); 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 A01204-1); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A01204-1) |
| Primary antibody | Rabbit anti-FGB, 2-5μg/ml (datasheet A01204-1) |
| Primary incubation | Overnight at 4 °C (datasheet A01204-1) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet A01204-1) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | FGB-positive staining in proximal tubules (cell body) of kidney (HPA tissue IHC: Medium). HPA tissue profile: Strong positivity in plasma and extracellular compartments. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA pH 8.0 retrieval for the catalog antibody (datasheet: A01204-1); the thrombus article does not specify a retrieval buffer (PMC12679381).
Section 2
What Is the Expected FGB Staining Pattern?
FGB is a secreted, non-transmembrane protein detected in blood plasma (UniProt P02675 topology; UniProt P02675 tissue specificity). In paraffin-section IHC, expect strong staining in plasma and extracellular compartments, with medium staining reported in kidney proximal tubule cell bodies (HPA: Enhanced tissue IHC; HPA: tissue profile; HPA: kidney). Because FGB is secreted, tissue RNA and protein locations can differ (HPA: reliability description).
| Strong plasma and extracellular staining, with medium proximal tubule cell-body staining in kidney (HPA: tissue IHC). | This matches the reported IHC pattern (HPA: tissue profile; HPA: kidney). Extracellular signal also fits FGB secretion and its presence in plasma (UniProt P02675). Assess tubule cell bodies separately from nearby plasma or extracellular staining when scoring (standard IHC practice). |
| Predominantly nuclear or sharply membrane-bound staining, without the expected extracellular pattern (HPA: tissue profile; UniProt P02675 topology). | Treat this as a localization mismatch requiring verification: FGB is secreted and has no transmembrane segment (UniProt P02675 topology). Review morphology and controls before assigning the signal to FGB (standard IHC practice). The mismatch alone does not identify the source of artefact. |
| Strong cell-body staining in HPA-listed negative populations, such as adipocytes or adrenal glandular cells (HPA: tissue IHC). | Investigate cross-reactivity or endogenous chromogen-generating activity using controls (standard IHC practice). HPA reports FGB as not detected in those cell types; that designation does not exclude plasma or extracellular staining elsewhere in the section (HPA: tissue IHC; HPA: tissue profile). |
| Broad chromogen haze obscures cell and extracellular boundaries (standard IHC practice). | The slide cannot be scored confidently against the HPA plasma and extracellular pattern (HPA: tissue profile). Check background in the negative control, then review blocking, washes and detection conditions as general IHC troubleshooting steps (standard IHC practice). |
| No signal in kidney proximal tubule cell bodies or in the expected plasma and extracellular compartments (HPA: kidney; HPA: tissue profile). | A negative result needs a run-level check before biological interpretation (standard IHC practice). HPA reports medium proximal tubule staining and strong plasma/extracellular positivity, but its profile does not establish a fixation-specific cause for absent signal (HPA: tissue IHC). |
💡Expected FGB appearanceCall the IHC result pattern-consistent when plasma and extracellular compartments stain strongly and kidney proximal tubule cell bodies show medium staining; isolated nuclear or crisp membrane-only signal warrants review (HPA: tissue IHC; UniProt P02675 topology).
| Secretion and tissue source (UniProt P02675; HPA: reliability description) | FGB is secreted and detected in plasma, so extracellular protein can appear away from its site of synthesis (UniProt P02675; HPA: reliability description). Do not equate local IHC signal with local FGB RNA expression. |
| Reported cell-type pattern (HPA: tissue IHC) | Kidney proximal tubule cell bodies are medium positive, while listed adipocytes and adrenal glandular cells are not detected (HPA: tissue IHC). Interpret each cell population separately from adjacent extracellular staining (HPA: tissue profile; standard IHC practice). |
| Processing and epitope position (UniProt P02675 processing) | UniProt places the signal peptide at residues 1–30 and the fibrinogen beta chain at 45–491 (UniProt P02675). If an antibody's epitope is known, check whether it lies in the mature chain; no epitope is supplied here. |
| Fibrin deposition (UniProt P02675 function) | Thrombin-cleaved fibrinogen contributes to an insoluble fibrin matrix in clots and wound repair (UniProt P02675 function). Extracellular staining in that setting can be biologically plausible, but this record does not establish which molecular form a given antibody detects. |
| IF/ICC: what localization should be expected? (HPA: subcellular ICC-IF) | HPA reports enhanced endoplasmic-reticulum localization in ICC-IF and lists Hep-G2 and U2OS image sets (HPA: subcellular ICC-IF). This is a separate cellular observation; the tissue IHC expectation remains strong plasma and extracellular staining (HPA: tissue profile). |
| Antibody evidence (HPA: antibody validation) | HPA001900 and HPA001901 are Enhanced for IHC; CAB008624 is Supported (HPA: antibody validation). These ratings support use of the reported pattern as a comparison, but do not specify a dilution, retrieval method or fixation effect. |
| Situation | Likely cause | Next action |
|---|---|---|
| Expected plasma and extracellular staining is absent (HPA: tissue profile). | The staining run, detection step or tissue material may need checking (standard IHC practice); the supplied sources identify no FGB-specific fixation effect. | Inspect the run's controls and section quality, then follow the selected antibody's documented IHC-P conditions (standard IHC practice). Do not infer FGB-specific retrieval requirements from HPA staining levels. |
| Kidney tubules appear positive only at their borders (HPA: kidney). | Adjacent extracellular or plasma staining may be mistaken for proximal tubule cell-body signal (HPA: tissue profile; standard IHC practice). | Review cell morphology at higher magnification and score cell bodies apart from extracellular spaces (standard IHC practice); compare with HPA's medium proximal tubule cell-body finding (HPA: kidney). |
| Adipocytes or adrenal glandular cells stain strongly (HPA: tissue IHC). | Cross-reactivity or endogenous detection activity is possible (standard IHC practice); HPA lists these cells as not detected (HPA: tissue IHC). | Compare a no-primary control and the IHC-validated antibody's controls, then reassess the cellular location (standard IHC practice). Retain separately located plasma or extracellular staining in the interpretation (HPA: tissue profile). |
| The section has diffuse chromogen background (standard IHC practice). | Nonspecific detection or insufficient blocking or washing may obscure the expected pattern (standard IHC practice; HPA: tissue profile). | Check the no-primary control and review blocking, washing and detection settings (standard IHC practice). Score FGB only where staining remains anatomically distinguishable. |
| Most signal is nuclear or confined to crisp cell membranes (UniProt P02675 topology). | That distribution conflicts with the secreted, non-transmembrane annotation and HPA extracellular profile (UniProt P02675 topology; HPA: tissue profile). | Recheck morphology, control staining and antibody validation before interpreting the compartment as FGB (standard IHC practice; HPA: antibody validation). |
| An IF/ICC image looks intracellular rather than extracellular (HPA: subcellular ICC-IF; HPA: tissue profile). | HPA reports endoplasmic-reticulum localization in ICC-IF, while tissue IHC shows strong plasma and extracellular positivity (HPA: subcellular ICC-IF; HPA: tissue profile). | Compare the image with the ICC-IF localization record and interpret tissue IHC against its separate tissue profile (HPA: subcellular ICC-IF; HPA: tissue IHC). |
Experiment evidence
IHC & IF images showing FGB staining
A01204-1 · IHCIHC analysis of Fibrinogen Beta Chain/FGB using anti-Fibrinogen Beta Chain/FGB antibody (A01204-1). Fibrinogen Beta Chain/FGB was detected i
A01204-1 · IFIF analysis of Fibrinogen beta chain/FGB using anti-Fibrinogen beta chain/FGB antibody (A01204-1). Fibrinogen beta chain/FGB was detected in
M01204-1 · IHCIHC analysis of Fibrinogen beta chain/FGB using anti-Fibrinogen beta chain/FGB antibody (M01204-1). Fibrinogen beta chain/FGB was detected i
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000171564-FGB/tissue/cerebral+cortex#imid_783120
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000171564-FGB/tissue/colon#imid_783046
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000171564-FGB/tissue/liver#imid_800119
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000171564-FGB/tissue/kidney#imid_783048
HPA · ICC-IF Hep-G2Human Protein Atlas immunofluorescence, Hep-G2, antibody HPA001900; green = FGB, blue = nucleus, red = microtubules.
HPA · ICC-IF Hep-G2Human Protein Atlas immunofluorescence, Hep-G2, antibody HPA001900; green = FGB, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for FGB IHC & IF
🧪Run kidney first and look for staining in proximal tubule cell bodies (HPA: Medium in kidney proximal tubules). Use adipose tissue as the negative comparison, assessing adipocytes (HPA: Not detected in adipocytes); on the kidney slide, assess neighboring areas without proximal tubule cell-body staining as internal background, without assuming every other renal cell type is negative.
Positive control tissue: Kidney (Proximal tubules (cell body), HPA Medium)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show FGB in Hep-G2, U2OS, with annotated localisation: Endoplasmic reticulum (enhanced) (HPA subcellular).
Technical controls: Include no-primary (secondary-only) and host-matched rabbit IgG isotype controls (A01204-1 caption: rabbit primary antibody), plus an FGB-knockout specimen as a biological negative if available. Block endogenous peroxidase for chromogenic kidney IHC and assess renal autofluorescence separately if using IF (standard IHC/IF practice).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected A01204-1 paraffin-section caption does not state a fixative (A01204-1 caption: fixative unreported). Heat retrieval in EDTA at pH 8.0 is a documented IHC starting condition, but retrieval dependency and whether frozen sections or IF are easier are unreported (A01204-1 caption: heat-mediated EDTA retrieval). Interpret vascular or luminal staining cautiously because circulating FGB may contribute signal alongside the reported proximal tubule cell-body staining (UniProt P02675: detected in blood plasma; HPA: Medium in kidney proximal tubules).
HPA tissue IHC evidence for FGB
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — At least one protein variant secreted, tissue location of RNA and protein might differ and correlation is complex.). Rows are taken directly from the HPA tissue chart — click any row's HPA link to view the source.
Positive expression · recommended positive controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Kidney | Proximal tubules (cell body) | Medium | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Adrenal gland | Glandular cells | Not detected | Protein (IHC) | HPA → |
| Appendix | Glandular cells | Not detected | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Breast | Adipocytes | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced FGB IHC Tips
Troubleshoot FGB staining in paraffin sections by checking retrieval, compartment, and extracellular signal before assigning staining to individual cells (UniProt P02675; HPA tissue IHC).
Which retrieval condition should I start with for FGB IHC?
Start with heat-mediated antigen retrieval in EDTA at pH 8.0 for this catalog antibody (datasheet A01204-1). The selected paraffin-section image used that condition, followed by 10% goat serum block and 2 μg/ml primary antibody overnight at 4°C (caption A01204-1). If staining is weak, compare a second retrieval condition on matched sections while holding antibody concentration and detection constant; inspect tissue morphology alongside signal (standard IHC practice). Score plasma and extracellular staining separately from cell-associated staining, because FGB is secreted and the HPA tissue profile reports strong positivity in those compartments (UniProt P02675; HPA tissue IHC).
Could fixation explain weak FGB staining in my paraffin sections?
Target-specific fixation sensitivity is unknown: the selected paraffin-section caption does not state a fixative, so its staining cannot establish an optimal fixation method (caption A01204-1). Record the fixative and fixation duration for each specimen, then compare similarly processed sections before changing retrieval or primary-antibody concentration (standard IHC practice). Use the documented EDTA pH 8.0 retrieval as a consistent starting condition when evaluating those sections (datasheet A01204-1). Check preserved morphology and compare extracellular with cell-associated signal; the expected plasma and extracellular distribution can complicate judgments based only on staining intensity (HPA tissue IHC; standard IHC practice).
Where should convincing FGB staining appear in tissue IHC?
Expect substantial plasma and extracellular staining, because FGB is secreted and the HPA tissue profile reports strong positivity in those compartments (UniProt P02675; HPA tissue IHC). FGB has no transmembrane segment, so a crisp membrane-only pattern should prompt review of morphology and controls (UniProt P02675 topology; standard IHC practice). The HPA profile also reports medium staining in kidney proximal tubule cell bodies; do not treat that observation as proof of local synthesis in every stained cell (HPA tissue IHC; standard IHC practice). Examine cell-associated staining alongside nearby extracellular material on the same section, and document each compartment separately when reporting results (standard IHC practice).
How do FGB processing and modifications affect epitope interpretation?
The record lists 0 isoforms and a signal peptide at residues 1–30, while the annotated beta chain spans residues 45–491 (UniProt P02675). It also reports glycosylation at residue 394 and a modified residue at 31; antibody epitope coordinates are not supplied here (UniProt P02675; caption A01204-1). Therefore, avoid assigning a failed stain to either modification or claiming the antibody distinguishes precursor from processed chain without epitope evidence (standard IHC interpretation). Compare staining under the documented EDTA pH 8.0 retrieval with appropriate controls before attributing a compartment difference to molecular processing (datasheet A01204-1; standard IHC practice).
How should I adapt FGB localisation checks for multiplex IF?
For the separate IF/ICC workflow, pair FGB with a marker identifying the cell population being evaluated, and inspect the FGB channel for overlap with that population (standard IF practice). Choose fluorophores after checking tissue autofluorescence in an unstained control, reserving a channel with clearer separation for the weaker signal (standard IF practice). FGB is secreted and has no transmembrane segment, while HPA reports an enhanced endoplasmic reticulum location in its subcellular data (UniProt P02675; HPA subcellular). If testing intracellular epitopes, assess permeabilisation on matched samples; extracellular FGB should also be evaluated without permeabilisation, since the antibody epitope is unspecified here (standard IF practice; caption A01204-1).
What should I check when FGB DAB staining looks diffuse?
First compare the diffuse signal with tissue architecture: strong plasma and extracellular positivity is reported for FGB and need not indicate nonspecific antibody binding (HPA tissue IHC). The selected paraffin-section workflow used 10% goat serum block, 2 μg/ml primary antibody overnight at 4°C, and DAB detection (caption A01204-1). If background obscures structures, check a no-primary control, peroxidase blocking, wash stringency, and DAB development while keeping the documented retrieval condition fixed (standard IHC practice; datasheet A01204-1). Compare section edges and damaged areas with intact regions before adjusting antibody concentration; nonspecific deposition can follow local tissue damage (standard IHC practice).
How should I quantify FGB IHC when extracellular staining dominates? ⚠ ANSWER MARKED FOR VERIFICATION
Define the measurement compartment before scoring: HPA reports strong plasma and extracellular FGB positivity, which can inflate a cell-based score (HPA tissue IHC; standard IHC practice). For cell-associated staining, report the percentage of positive cells and an H-score with explicit intensity categories; normalise counts to the number of evaluable cells (standard IHC practice). For extracellular deposits, measure positive area or integrated optical density and normalise to evaluable tissue area in mm², excluding vessels or other compartments if the question requires it (standard IHC practice). Apply the same threshold, region-selection rules, and DAB development conditions across compared sections (standard IHC practice).
How can I distinguish genuine FGB signal from IHC artefact?
A plausible FGB pattern includes plasma or extracellular material, consistent with its secreted annotation and the HPA tissue profile (UniProt P02675; HPA tissue IHC). Isolated membrane-only staining is less consistent with its lack of a transmembrane segment, so inspect a matched control and the surrounding morphology (UniProt P02675 topology; standard IHC practice). Check edge-concentrated deposits, necrotic areas, and a no-primary control before assigning unusual cell staining to FGB; also verify that peroxidase blocking controls endogenous enzyme signal (standard IHC practice). Report cell-associated staining separately from adjacent deposits, because proximity alone cannot establish which cells produced a secreted protein (UniProt P02675; standard IHC interpretation).
Boster reagents
Best FGB / Fibrinogen beta chain IHC Antibodies
Both anti-FGB antibodies have IHC images from paraffin sections of human liver cancer tissue (A01204-1 IHC caption; M01204-1 IHC caption); A01204-1 also has an IF image from A549 cells (A01204-1 IF caption).
Real IHC data
Anti-Fibrinogen beta chain/FGB Antibody ®
Cat # A01204-1
Real IHC data
Anti-Fibrinogen beta chain/FGB Antibody ® (monoclonal, 6D12)
Cat # M01204-1
A01204-1 has a human liver cancer paraffin-section IHC image and an A549 cell IF image (A01204-1 IHC and IF captions). M01204-1 has a human liver cancer paraffin-section IHC image and lists human reactivity (M01204-1 IHC caption; M01204-1 catalog reactivity).
Which to pick: For human tissue IHC, either SKU has a paraffin-section image; A01204-1 is rabbit and M01204-1 is mouse monoclonal clone 6D12 (each SKU’s IHC caption; catalog host and clone). For IF/ICC, choose A01204-1, which lists both applications and has an A549 cell IF image (A01204-1 applications; A01204-1 IF caption). For mouse or rat work, A01204-1 lists reactivity with those species, but its supplied IHC image is human; neither IHC caption reports the fixative (A01204-1 catalog reactivity; A01204-1 IHC caption; M01204-1 IHC caption).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P02675 (FIBB_HUMAN, Fibrinogen beta chain).
- Human Protein Atlas. FGB tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. FGB subcellular location (ICC-IF): Localized to the endoplasmic reticulum..
- Human Protein Atlas. FGB antibody validation summary (3 antibodies).
- Histological analysis of thrombus composition in acute ischemic stroke with large vessel occlusion: impact of r-tPA treatment. Frontiers in neuroscience 2025 — PMC12679381.
- Pleural thickening induced by Glaesserella parasuis infection was linked to increased collagen and elastin. Frontiers in cellular and infection microbiology 2022 — PMC9409878.
- Bioinformatics analysis of the proteome in the pathway of complement and coagulation cascades in COVID-19: discovering potential biomarkers of FGB and SERPINA5. BMC infectious diseases 2025 — PMC12506357.
- Bioprosthetic Valve Deterioration: Accumulation of Circulating Proteins and Macrophages in the Valve Interstitium. JACC. Basic to translational science 2023 — PMC10401294.
- PubMed PMID:6688356 — UniProt-cited evidence.
- PubMed PMID:2102623 — UniProt-cited evidence.
- PubMed PMID:14702039 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for FGB (Fibrinogen beta chain). Expected localisation Plasma and extracellular compartments (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A01204-1). Validated IHC antibody: A01204-1 at 2-5μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Kidney (Proximal tubules (cell body)); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human liver cancer tissue; fixative not specified (datasheet A01204-1); 2. Fixation: Image fixative and duration unreported (datasheet A01204-1); 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 A01204-1); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A01204-1); 8. Primary antibody: Rabbit anti-FGB, 2-5μg/ml (datasheet A01204-1); 9. Primary incubation: Overnight at 4 °C (datasheet A01204-1). Watch for: Fixation: Keep fixation consistent across sections. (standard IHC practice; not target-specific); Caveat: Extracellular signal may not identify producing cells (HPA tissue IHC); Isoform / epitope: No listed isoforms; mature chain 45–491 (UniProt); Regulation: Liver-enriched RNA; protein may differ (HPA tissue RNA). Evidence: UniProt P02675, HPA tissue IHC · Enhanced, HPA ICC-IF · endoplasmic reticulum., Datasheet A01204-1, PMC12679381, PMC10401294. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/FGB/immunohistochemistry-ihc-guide.