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FDCSP / Follicular dendritic cell secreted peptide · IHC design guide
Design Immunohistochemistry for FDCSP
Plan chromogenic paraffin IHC for FDCSP using tonsil squamous epithelium as a positive reference (HPA tissue IHC). This guide covers the IHC-validated antibody at 0.5–1 μg/mL (datasheet A13093-1), fixation consistency, detection, and interpretation of a secreted target (UniProt).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
FDCSP 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 | Secreted; tissue compartment unresolved (UniProt; HPA tissue IHC) | |
| Staining pattern | Tonsil squamous; salivary glandular; compartment unclear (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6 HIER, heat-mediated (datasheet A13093-1) | |
| Positive control | Tonsil+1 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 | Secretion can separate protein staining from RNA location (HPA tissue IHC) | |
| Regulation | Tissue-specific expression (UniProt) | |
| Isoform / epitope | 0 isoforms; signal peptide cleaved, no cytoplasmic tail (UniProt) |
Section 1
Recommended FDCSP IHC & IF Protocols
The catalog antibody’s IHC-P protocol (datasheet A13093-1) is accompanied by a published breast tissue IHC protocol (PMC12507714).
| Sample | Paraffin-embedded human tonsil tissues; fixative not specified (datasheet A13093-1) |
| Fixation | Image fixative and duration unreported (datasheet A13093-1); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat retrieval: Citrate pH 6, 20 min (datasheet A13093-1) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A13093-1) |
| Primary antibody | Rabbit anti-FDCSP, 0.5-1μg/ml (datasheet A13093-1) |
| Primary incubation | Overnight at 4 °C (datasheet A13093-1) |
| Detection | Streptavidin-biotin complex (SABC), DAB chromogen (datasheet A13093-1) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | FDCSP-positive staining in squamous epithelial cells of tonsil (HPA tissue IHC: High). HPA tissue profile: Distinct expression was observed in the squamous epithelium of tonsil and salivary gland. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated citrate retrieval at pH 6 (datasheet A13093-1); the published breast tissue protocol also specifies citrate at pH 6.0 (PMC12507714).
Section 2
What Is the Expected FDCSP Staining Pattern?
FDCSP is a secreted peptide with no transmembrane segment (UniProt Q8NFU4 topology). In paraffin-section IHC, expect the clearest staining in tonsil squamous epithelial cells and weaker staining in salivary gland glandular cells (HPA: High; Medium). Its secreted status permits protein to appear beyond its producing cells (UniProt Q8NFU4; HPA reliability note). HPA rates the tissue pattern Enhanced, with medium consistency against RNA data and external verification pending (HPA reliability).
| Strong staining in tonsil squamous epithelium, with moderate staining in salivary gland glandular cells. | This matches the reported cell types and relative levels (HPA: tonsil High; salivary gland Medium). Assess the stained cells as well as intensity: surrounding deposited secreted protein may complicate assignment to its source (UniProt Q8NFU4 secreted; HPA reliability note). |
| Predominantly nuclear staining, or a sharply defined membrane pattern presented as the only convincing signal. | Neither is an established FDCSP location here: HPA lists no ICC-IF main location, and UniProt describes a secreted peptide without a transmembrane segment (HPA subcellular; UniProt Q8NFU4 topology). Treat the pattern as suspect and check controls before scoring it as specific. |
| Strong staining in adipocytes, marrow hematopoietic cells, or bronchial respiratory epithelium. | Those cell populations were not detected in the supplied tissue survey (HPA: adipose tissue, bone marrow, bronchus). Check antibody-dependent staining and, for chromogenic IHC, endogenous detection activity using appropriate controls (standard IHC practice). |
| Broad, low-contrast colour across cells and surrounding tissue, obscuring epithelial boundaries. | Diffuse background prevents a reliable comparison with the reported tonsil and salivary gland pattern (HPA tissue IHC). Review blocking, washing, primary-antibody concentration and chromogen development with matched controls (standard IHC practice); do not assign every extracellular deposit to FDCSP merely because it is secreted (UniProt Q8NFU4). |
| No staining in tonsil squamous epithelial cells on the test section. | Tonsil squamous epithelium is the strongest supplied positive reference (HPA: High). First verify tissue identity and that a known-positive control worked, then review retrieval, detection and antibody conditions as general IHC checks (standard IHC practice). The supplied sources do not identify an FDCSP-specific retrieval condition. |
💡Expected FDCSP appearanceCall a result positive when tonsil squamous epithelial cells show strong, interpretable staining, with salivary gland glandular cells typically weaker (HPA: High; Medium); isolated nuclear or unexpected-cell staining is suspect, while the exact subcellular pattern remains unestablished (HPA subcellular; UniProt Q8NFU4 topology).
| Secretion and topology (UniProt Q8NFU4). | FDCSP has a signal peptide and no transmembrane segment (UniProt Q8NFU4 topology). Cell-associated staining can support the expected pattern, but nearby extracellular signal need not mark the cell that produced it (UniProt Q8NFU4 secreted; HPA reliability note). |
| Processing (UniProt Q8NFU4). | The annotated signal peptide spans residues 1–17 and the mature chain spans 18–85 (UniProt Q8NFU4 processing). Epitope position is not supplied, so do not infer whether the catalog antibody recognizes precursor, mature peptide, or both. |
| Tissue contrast (HPA tissue IHC). | Use tonsil squamous epithelium as the strongest supplied positive reference and salivary gland glandular cells as a second, moderate reference (HPA: High; Medium). Lymph-node germinal-center cells are reported Low, so faint staining there is less decisive (HPA: Low). |
| Evidence strength (HPA tissue IHC). | The tissue profile is rated Enhanced, and both listed antibodies have Enhanced IHC status (HPA reliability; HPA antibodies: HPA014326, CAB014890). RNA and antibody staining have medium consistency, and external verification is pending (HPA reliability); interpret discordant fields cautiously. |
| IF localisation evidence (HPA subcellular). | HPA calls FDCSP secreted but provides no main ICC-IF location or cell-line images (HPA subcellular). The tissue IHC profile therefore cannot specify an IF puncta, membrane, or nuclear pattern; evaluate IF/ICC on its separate guide page. |
| Situation | Likely cause | Next action |
|---|---|---|
| Tonsil positive control is blank or very weak. | The run has not reproduced the reported High signal in tonsil squamous epithelial cells (HPA: High); the record does not establish an FDCSP-specific technical cause. | Confirm the squamous epithelium is present, then check antibody use, retrieval, detection reagents and run controls under the IHC protocol (standard IHC practice). Avoid declaring the tissue negative until the control works. |
| Salivary gland stains more strongly than tonsil. | That reverses the supplied relative tissue levels, although section and run differences can affect apparent intensity (HPA: tonsil High; salivary gland Medium; standard IHC practice). | Compare the stated cell populations under matched staining and scoring conditions, with a tonsil control in the same run (HPA tissue IHC; standard IHC practice). |
| Unexpected staining appears in a reported negative cell population. | Cross-reactivity or endogenous chromogenic detection activity is possible (standard IHC practice); the supplied HPA survey reports several such populations as Not detected (HPA tissue IHC). | Inspect a no-primary control and the relevant endogenous-activity control; compare the unexpected signal with the tonsil pattern before assigning specificity (standard IHC practice; HPA: tonsil High). |
| Colour is widespread, faint and hard to localise. | Nonspecific background or excessive development can obscure interpretable cell staining (standard IHC practice). FDCSP secretion alone does not validate an indiscriminate diffuse pattern (UniProt Q8NFU4 secreted). | Review primary-antibody dilution, blocking, washes and development against controls (standard IHC practice); score only signal that can be assigned reliably to the reported cells (HPA tissue IHC). |
| Lymph node is faint while tonsil is clearly positive. | This can agree with the survey: germinal-center cells in lymph node are Low, versus High tonsil squamous epithelial staining (HPA tissue IHC). | Use tonsil for the primary positive check, and describe lymph-node staining by its observed cell population and intensity rather than requiring tonsil-level signal (HPA: tonsil High; lymph node Low). |
| Can the IHC result define the expected IF/ICC pattern? | No ICC-IF main location or image-bearing cell lines are supplied, despite the secreted summary (HPA subcellular). | Use the separate IF/ICC guide for that application; do not transfer a chromogenic tissue pattern into a required IF compartment or invent an IF protocol (HPA subcellular; HPA tissue IHC). |
Experiment evidence
IHC & IF images showing FDCSP staining
A13093-1 · IHCIHC analysis of FDCSP using anti-FDCSP antibody (A13093-1). FDCSP was detected in paraffin-embedded section of human tonsil tissues. Heat me
A13093-1 · IFIF analysis of FDCSP using anti-FDCSP antibody (A13093-1). FDCSP was detected in a paraffin-embedded section of human tonsil tissue. Heat me
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000181617-FDCSP/tissue/cerebral+cortex#imid_4177204
HPA · Salivary glandHuman Protein Atlas IHC, Salivary gland. Source: https://www.proteinatlas.org/ENSG00000181617-FDCSP/tissue/salivary+gland#imid_4177136
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000181617-FDCSP/tissue/colon#imid_4177122
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000181617-FDCSP/tissue/liver#imid_4177131
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for FDCSP IHC & IF
🧪Run tonsil first; its squamous epithelial cells should stain (HPA: High in tonsil squamous epithelial cells). Use adipose tissue as the negative tissue; its adipocytes should lack specific staining (HPA: Not detected in adipocytes), while cells without signal on the tonsil slide can serve as internal negative regions without assigning them a specific HPA-validated cell identity.
Positive control tissue: Tonsil (Squamous epithelial cells, HPA High)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA carries no ICC-IF cell line for FDCSP; derive a cell-line control from the positive tissue's cell type (Squamous epithelial cells) and confirm it by RNA or western blot first.
Technical controls: Include no-primary (secondary-only) and host-matched rabbit IgG isotype controls, plus a biological negative such as FDCSP knockout tissue if available or peptide competition (caption: rabbit anti-FDCSP primary; standard IHC practice). Check endogenous peroxidase and biotin background in tonsil because the reported detection uses a biotinylated secondary, streptavidin complex, and DAB (caption: tonsil IHC detection).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected paraffin-section caption does not state the fixative (caption: fixative unreported). The reported tonsil IHC used citrate retrieval at pH 6 for 20 minutes; whether retrieval is required under other conditions is unreported (caption: tonsil IHC). Whether frozen sections or IF/ICC are easier is unreported; the supplied example is paraffin IHC, and HPA lists no ICC-IF cell-line images (caption: paraffin tonsil section; HPA: subcellular record).
HPA tissue IHC evidence for FDCSP
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Enhanced — Medium consistency between antibody staining and RNA expression data. Pending external verification. Secreted protein, tissue location of RNA and protein is expected to differ.). Rows are taken directly from the HPA tissue chart — click any row's HPA link to view the source.
Positive expression · recommended positive controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Tonsil | Squamous epithelial cells | High | Protein (IHC) | HPA → |
| Salivary gland | Glandular cells | 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 → |
| Bone marrow | Hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Breast | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced FDCSP IHC Tips
Troubleshoot FDCSP staining in paraffin sections using the catalog antibody’s tonsil IHC result and the reported tissue expression pattern.
What retrieval should I try first if FDCSP staining is weak in paraffin sections?
Start with heat-mediated citrate retrieval at pH 6 for 20 minutes (datasheet A13093-1). The catalog antibody detected FDCSP in a paraffin-embedded human tonsil section after this treatment (datasheet A13093-1). Run a tonsil control alongside the test sections, keeping retrieval temperature, cooling, and section thickness consistent across the batch (standard IHC practice; datasheet A13093-1: tonsil). If staining remains weak, vary heating or cooling incrementally and compare tissue preservation before changing buffer chemistry (standard IHC practice). Because FDCSP is secreted, assess both cellular and nearby extracellular staining when judging whether retrieval helped (UniProt Q8NFU4: secreted).
How should I assess whether fixation is suppressing FDCSP staining?
The selected tonsil caption identifies paraffin-embedded tissue but does not report its fixative, so target-specific fixation sensitivity is unknown (datasheet A13093-1: fixative not stated). Record the fixative, time before fixation, fixation duration, and processing conditions for each block before attributing weak staining to fixation (standard IHC practice). Compare affected sections with a consistently processed tonsil control using the documented pH 6, 20-minute retrieval condition (datasheet A13093-1). Keep section thickness and detection conditions matched, then assess whether tissue morphology and control staining vary together (standard IHC practice). Neither reported tissue expression nor predicted secretion establishes a fixation effect (HPA: tissue IHC; UniProt Q8NFU4: secreted).
Which staining compartments are plausible for FDCSP in tonsil?
Interpret tonsil staining with a secreted protein in mind: the annotated FDCSP precursor has a signal peptide at residues 1–17 and a mature chain at 18–85 (UniProt Q8NFU4). Its topology has no transmembrane segment, so membrane-bound staining alone should not define a positive cell (UniProt Q8NFU4: topology). HPA reports high staining in tonsillar squamous epithelial cells and medium staining in salivary glandular cells (HPA: tissue IHC). Examine epithelial cytoplasm, adjacent extracellular material, and the boundary between stained and unstained cells while preserving anatomical context (UniProt Q8NFU4: secreted; standard IHC practice). A deposit away from a producing cell needs corroboration because secreted protein can separate protein location from RNA location (HPA: reliability description).
How should epitope uncertainty affect interpretation of a negative section?
FDCSP has one listed mature chain, residues 18–85, following a 1–17 signal peptide; no isoforms, glycosylation sites, or modified residues are annotated (UniProt Q8NFU4). The supplied evidence does not map the catalog antibody’s epitope, so a negative section cannot identify which portion of the precursor failed to stain (datasheet A13093-1: epitope not supplied). Check whether the tonsil control stains under the documented 1 μg/mL overnight primary incubation and citrate pH 6 retrieval (datasheet A13093-1). If the control works, interpret a negative test section against its cell composition and tissue context rather than assuming an alternative isoform (UniProt Q8NFU4: no annotated isoforms; HPA: tissue IHC).
How can I investigate FDCSP localisation by multiplex IF?
Use the chromogenic tonsil result to choose a region, then validate IF staining independently because the supplied HPA record lists no ICC/IF images (datasheet A13093-1: tonsil IHC; HPA: subcellular record). Multiplex with a validated squamous epithelial marker in tonsil, or a glandular cell marker in salivary gland, to identify the expected cells (HPA: tissue IHC). Choose a far-red FDCSP fluorophore and inspect unstained tissue for autofluorescence before interpreting overlap (standard IF practice). Because mature FDCSP is secreted and has no transmembrane segment, compare staining without detergent for accessible extracellular epitopes against mild permeabilisation for intracellular secretory-pathway signal (UniProt Q8NFU4: secreted, topology; standard IF practice). Do not treat the 1 μg/mL IHC incubation as an IF-validated dilution (datasheet A13093-1).
What should I check when FDCSP DAB staining looks diffuse?
Begin with a no-primary control and inspect whether brown signal follows tissue edges, necrotic areas, or the entire section (standard chromogenic IHC practice). The documented tonsil workflow used 10% goat serum blocking, 1 μg/mL primary antibody overnight at 4°C, and biotin-based DAB detection (datasheet A13093-1). Confirm adequate peroxidase blocking and washing; these are general chromogenic controls, not demonstrated FDCSP-specific requirements (standard chromogenic IHC practice). Review the no-primary control for detection-system signal before reducing primary concentration or DAB development (standard chromogenic IHC practice). Genuine extracellular FDCSP remains possible, but diffuse staining should be judged against control sections and the expected epithelial pattern (UniProt Q8NFU4: secreted; HPA: tissue IHC).
How should I score FDCSP staining across paraffin tissue sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the compartment and cell population before scoring: HPA reports high tonsillar squamous epithelial staining and medium salivary glandular staining (HPA: tissue IHC). For cell-associated DAB signal, record the percentage of positive eligible cells and an intensity-based H-score; retain extracellular deposits as a separate measure (standard IHC scoring practice; UniProt Q8NFU4: secreted). Alternatively, report positive area per mm² of evaluable tissue when cell boundaries cannot be assigned reliably (standard image-analysis practice). Normalise cell counts to the relevant epithelial or glandular population, and area measures to intact evaluable tissue, excluding folds and necrosis (standard IHC scoring practice). Keep threshold, counterstain, imaging, and control-slide settings consistent across groups (standard image-analysis practice).
How can I distinguish genuine FDCSP signal from chromogenic artefact?
A credible result should reproduce in an appropriate control and align with the reported tonsillar squamous epithelial or salivary glandular pattern (HPA: tissue IHC). Check whether staining is cellular or nearby extracellular, since FDCSP is secreted and lacks a transmembrane segment (UniProt Q8NFU4: secreted, topology). Treat isolated nuclear staining, uniform section-edge staining, and deposits confined to necrosis as suspect until repeat sections and controls resolve them (standard IHC practice). A no-primary section helps identify detection or endogenous-enzyme signal; review peroxidase blocking when brown staining persists without primary antibody (standard chromogenic IHC practice). HPA rates its tissue evidence Enhanced but notes medium RNA–protein consistency and pending external verification, so interpret unexpected sites cautiously (HPA: reliability description).
Boster reagents
Best FDCSP / Follicular dendritic cell secreted peptide IHC Antibodies
Anti-FDCSP antibody A13093-1 has IHC and IF images from human paraffin-embedded tonsil sections (catalog IHC and IF captions).
Real IHC data
Anti-FDCSP Antibody
Cat # A13093-1
A13093-1 was tested by chromogenic IHC on a human paraffin-embedded tonsil section (catalog IHC caption). A13093-1 was also tested by IF on a human paraffin-embedded tonsil section (catalog IF caption).
Which to pick: For tissue IHC, choose A13093-1 for human paraffin sections (catalog IHC caption; catalog reactivity: Human); the IHC caption does not report the fixative. For IF, A13093-1 has a human paraffin-section image, while ICC is not listed among its applications (catalog IF caption; catalog applications: IF, IHC). No cross-species choice is supported because A13093-1 lists human reactivity only (catalog reactivity: Human).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q8NFU4 (FDSCP_HUMAN, Follicular dendritic cell secreted peptide).
- Human Protein Atlas. FDCSP tissue IHC expression (reliability: Enhanced).
- Human Protein Atlas. FDCSP subcellular location (ICC-IF): Secreted.
- Human Protein Atlas. FDCSP antibody validation summary (2 antibodies).
- Identification of novel follicular dendritic cell sarcoma markers, FDCSP and SRGN, by whole transcriptome sequencing. Oncotarget 2017 — PMC5369977.
- Multi-omics analysis identifies the unique high-FDCSP basal cells in triple-negative breast cancer. Experimental biology and medicine (Maywood, N.J.) 2025 — PMC12507714.
- A novel oxidative stress-related gene signature as an indicator of prognosis and immunotherapy responses in HNSCC. Aging 2023 — PMC10781479.
- PubMed PMID:12193705 — UniProt-cited evidence.
- PubMed PMID:12975309 — UniProt-cited evidence.
- PubMed PMID:15489334 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for FDCSP (Follicular dendritic cell secreted peptide). Expected localisation Secreted; tissue compartment unresolved (UniProt; HPA tissue IHC). Antigen retrieval: Citrate pH 6 HIER, heat-mediated (datasheet A13093-1). Validated IHC antibody: A13093-1 at 0.5-1μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Tonsil (Squamous epithelial cells); negative Adipose tissue. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human tonsil tissues; fixative not specified (datasheet A13093-1); 2. Fixation: Image fixative and duration unreported (datasheet A13093-1); 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: Citrate pH 6 , 20 min (datasheet A13093-1); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A13093-1); 8. Primary antibody: Rabbit anti-FDCSP, 0.5-1μg/ml (datasheet A13093-1); 9. Primary incubation: Overnight at 4 °C (datasheet A13093-1). Watch for: Fixation: Keep fixation consistent across paraffin sections. (standard IHC practice; not target-specific); Caveat: Secretion can separate protein staining from RNA location (HPA tissue IHC); Isoform / epitope: 0 isoforms; signal peptide cleaved, no cytoplasmic tail (UniProt); Regulation: Tissue-specific expression (UniProt). Evidence: UniProt Q8NFU4, HPA tissue IHC · Enhanced, HPA ICC-IF · Secreted, Datasheet A13093-1, PMC12507714. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/FDCSP/immunohistochemistry-ihc-guide.