This website uses cookies to ensure you get the best experience on our website.
- Table of Contents
LNPEP / Leucyl-cystinyl aminopeptidase · IHC design guide
Design Immunohistochemistry for LNPEP
Plan chromogenic LNPEP IHC in paraffin sections with the IHC-validated antibody at 2–5 μg/mL (datasheet A05092-1). Assess cytoplasmic staining in glandular and neuronal cells, and consider the secreted form when interpreting extracellular signal (HPA tissue IHC; UniProt).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
LNPEP 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 | Cytoplasmic staining in most tissues; some plasma positivity (HPA tissue IHC) | |
| Staining pattern | Mostly cytoplasmic; plasma positivity in several tissues (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A05092-1) | |
| Positive control | Appendix+4 more · see all | |
| Negative control | None in HPA (detected in all 45 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 | Secreted pregnancy serum form may add extracellular signal (UniProt) | |
| Regulation | Insulin/oxytocin shifts LNPEP to the surface (UniProt) | |
| Isoform / epitope | 3 isoforms; cytoplasmic epitopes miss soluble form (UniProt) |
Section 1
Recommended LNPEP IHC & IF Protocols
The catalog antibody’s IHC protocol is paired with two published LNPEP protocols for equine paraffin sections (PMC8996865; PMC10030782).
| Sample | Paraffin-embedded human placenta tissue; fixative not specified (datasheet A05092-1) |
| Fixation | Image fixative and duration unreported (datasheet A05092-1); 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 A05092-1); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A05092-1) |
| Primary antibody | Rabbit anti-LNPEP, 2-5 μg/ml (datasheet A05092-1) |
| Primary incubation | Overnight at 4 °C (datasheet A05092-1) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet A05092-1) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | LNPEP-positive staining in glandular cells of appendix (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic expression in most tissues with additional plasma positivity in several tissues. No signal in the no-primary control. |
💡Decision noteStart with EDTA pH 8.0 heat retrieval for the catalog antibody (datasheet: A05092-1); the equine studies used citrate pH 6.0 with another antibody (PMC8996865; PMC10030782).
Section 2
What Is the Expected LNPEP Staining Pattern?
Expect mainly cytoplasmic LNPEP staining across many tissues, with plasma positivity in several (HPA tissue IHC). LNPEP is a membrane protein whose 111–131 transmembrane segment separates a cytoplasmic N terminus from an extracellular C terminus; it also resides in intracellular vesicles and may reach the cell surface (UniProt Q9UIQ6 topology and subcellular location). HPA rates the tissue staining Approved but reports low consistency with RNA expression (HPA tissue IHC).
| Cytoplasmic signal in appendix or duodenal glandular cells. | This fits HPA's High staining in those cells and its broader cytoplasmic tissue pattern (HPA tissue IHC). Score the identified cells and their compartment alongside the chromogenic intensity; a dark field alone does not identify the stained cell (general IHC interpretation). |
| Predominantly nuclear signal, without the expected cytoplasmic pattern. | Nuclear staining is discordant with HPA's cytoplasmic tissue profile and UniProt's membrane and vesicle locations (HPA tissue IHC; UniProt Q9UIQ6 subcellular location). Treat it as suspect until controls and cell morphology support a specific signal; compartment mismatch alone cannot identify the artefact. |
| Strong signal in an unexpected cell population. | Compare cells within the same tissue: HPA reports High staining in bronchial basal cells and caudate neurons, but Low staining in thyroid glandular cells and liver cholangiocytes (HPA tissue IHC). Unexpected staining may reflect cross-reactivity or endogenous detection activity; morphology and controls must distinguish these explanations (general IHC practice). |
| Uniform brown haze over cells and surrounding tissue. | A diffuse field cannot be scored as LNPEP localisation merely because HPA describes cytoplasmic staining (HPA tissue IHC). Assess background with the primary antibody omitted, then review blocking, washing and chromogen development (general chromogenic IHC practice). |
| No signal in an appendix or duodenum section expected to stain. | HPA records High glandular-cell staining in both tissues, so an absent signal warrants a technical check (HPA tissue IHC). Confirm glandular cells are present, then check the antibody's IHC validation and the general staining workflow; HPA's low RNA–staining consistency limits any claim that every specimen must be positive (HPA tissue IHC). |
💡Expected LNPEP appearanceA persuasive positive shows cell-associated, mainly cytoplasmic chromogen in the relevant cells, such as High-staining appendix or duodenal glands (HPA tissue IHC), whereas isolated nuclear staining or a uniform brown haze is suspect against the reported compartment pattern (HPA tissue IHC; general IHC interpretation).
| Topology and compartment | LNPEP has a cytoplasmic 1–110 region, a 111–131 membrane span and an extracellular 132–1025 region (UniProt Q9UIQ6 topology). Epitope position would matter when interpreting surface versus intracellular access, but no epitope location is supplied for the antibody. |
| Vesicle trafficking | LNPEP resides in intracellular vesicles with GLUT4 and can translocate to the cell surface after insulin or oxytocin stimulation (UniProt Q9UIQ6 subcellular location). Cytoplasmic and membrane-associated appearances can therefore be biologically plausible; this record does not predict their proportions in a particular section. |
| Membrane and soluble forms | UniProt lists cell-membrane and secreted locations and a 155–1025 pregnancy-serum form; it reports only the membrane-bound form in brain (UniProt Q9UIQ6 subcellular location and processing). Extracellular-looking signal needs tissue context and controls before attribution to secreted LNPEP. |
| Tissue and cell context | HPA lists High staining in epididymal glandular cells and cerebral-cortex neurons, Medium staining in endometrial glandular cells, and Low staining in oral squamous epithelium (HPA tissue IHC). Use the named cell population when judging intensity; these categories do not define a universal cutoff. |
| Strength of staining evidence | HPA marks tissue staining Approved while noting low consistency with RNA expression; HPA043642 has Approved IHC status, with no Enhanced designation supplied (HPA tissue IHC; HPA antibody validation). The pattern is a useful reference, but a single staining result is insufficient to establish specificity. |
| IF/ICC evidence | HPA summarizes LNPEP as Membrane in ICC-IF but supplies no main location or cell-line images in this record (HPA subcellular ICC-IF). That summary cannot establish an IF pattern or conditions for this paraffin-section IHC assay. |
| Situation | Likely cause | Next action |
|---|---|---|
| Expected glandular cells are unstained. | The section may lack the relevant cells, or an IHC step may have failed; appendix and duodenal glandular cells are High in the HPA record (HPA tissue IHC). | Check morphology and a suitable positive section, then review the antibody's stated IHC conditions, retrieval, detection and chromogen steps (general IHC practice). No LNPEP-specific retrieval condition is supplied. |
| Nuclei dominate the staining. | That compartment conflicts with HPA's cytoplasmic profile and UniProt's membrane and vesicle locations (HPA tissue IHC; UniProt Q9UIQ6 subcellular location). | Compare the primary-omission control and inspect morphology before scoring; if nuclei remain the principal signal, report the pattern as discordant (general IHC interpretation). |
| Brown signal fills the slide evenly. | Diffuse background can arise from the detection workflow and does not reproduce HPA's cell-associated cytoplasmic profile (general IHC practice; HPA tissue IHC). | Inspect the primary-omission control, then check blocking, washing and chromogen development using the laboratory's standard chromogenic IHC workflow (general IHC practice). |
| Strong staining appears in an unexpected cell type. | Cross-reactivity or endogenous detection activity is possible; HPA's reported intensity is cell-type specific and its RNA–staining consistency is low (general IHC practice; HPA tissue IHC). | Verify cell identity on the counterstained section, compare the HPA cell-specific pattern, and review detection controls before assigning LNPEP positivity (HPA tissue IHC; general IHC practice). |
| A low-staining tissue has a weak signal. | Weak staining may be compatible with an HPA Low category: thyroid glandular cells, liver cholangiocytes and chondrocytes are listed as Low, not negative (HPA tissue IHC). | Score cell and compartment together and compare background controls; avoid using these Low entries as absolute negative controls (HPA tissue IHC; general IHC interpretation). |
| Can the IHC result predict an ICC-IF image? | The ICC-IF summary says Membrane, but this record provides no main location or cell-line images (HPA subcellular ICC-IF). | Use the separate IF/ICC guide for that application; describe the IHC slide from its observed cell and compartment pattern without claiming IF confirmation (HPA tissue IHC; HPA subcellular ICC-IF). |
Experiment evidence
IHC & IF images showing LNPEP staining
A05092-1 · IHCIHC analysis of LNPEP using anti-LNPEP antibody (A05092-1). LNPEP was detected in a paraffin-embedded section of human placenta tissue. Heat
A05092-1 · IHCIHC analysis of LNPEP using anti-LNPEP antibody (A05092-1). LNPEP was detected in a paraffin-embedded section of mouse brain tissue. Heat me
A05092 · IFImmunofluorescence of LNPEP in human lung tissue with LNPEP antibody at 20 μg/mL.
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000113441-LNPEP/tissue/cerebral+cortex#imid_12027595
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000113441-LNPEP/tissue/colon#imid_12027521
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000113441-LNPEP/tissue/liver#imid_12027538
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000113441-LNPEP/tissue/kidney#imid_12027539
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for LNPEP IHC & IF
🧪Run appendix first and look for staining in glandular cells (High; HPA: appendix glandular cells). HPA lists no negative tissue and detects LNPEP in all 45 scored tissues (HPA); use no-primary and isotype controls for the negative comparison, and assess unstained areas within the appendix section as background without assuming their cells lack LNPEP (standard IHC practice).
Positive control tissue: Appendix (Glandular cells, HPA High)
Negative control tissue: None in HPA: LNPEP is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead.
ICC-IF cell lines (HPA subcellular resource): HPA carries no ICC-IF cell line for LNPEP; derive a cell-line control from the positive tissue's cell type (Glandular cells) and confirm it by RNA or western blot first.
Technical controls: Run a no-primary, secondary-only slide and a concentration-matched rabbit IgG isotype control matched to the primary’s clonality; use LNPEP knockout tissue, if available, as a biological specificity control (caption: rabbit primary; standard IHC practice). For chromogenic appendix IHC, quench endogenous peroxidase and check endogenous biotin if using avidin–biotin detection (standard IHC practice).
⚠️Feasibility: No target-specific fixation window or fixation effect is reported in the supplied evidence, and the selected paraffin-section caption does not state its fixative (selected IHC caption). Heat retrieval in EDTA at pH 8.0 was used for the selected IHC example, but retrieval dependence has not been established (selected IHC caption). The evidence does not establish whether frozen sections or IF are easier; for appendix IHC, endogenous peroxidase is a potential source of background (standard IHC practice).
HPA tissue IHC evidence for LNPEP
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 |
|---|---|---|---|---|
| Appendix | Glandular cells | High | Protein (IHC) | HPA → |
| Bronchus | Basal cells | High | Protein (IHC) | HPA → |
| Caudate | Neuronal cells | High | Protein (IHC) | HPA → |
| Cerebellum | Cells in granular layer | High | Protein (IHC) | HPA → |
| Cerebral cortex | Neuronal cells | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| None in HPA: LNPEP is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead. | ||||
Section 3
Advanced LNPEP IHC Tips
Troubleshoot LNPEP staining in paraffin sections by checking retrieval, compartment, cell identity and controls before comparing staining intensity.
What should I change when LNPEP staining is weak after antigen retrieval?
Begin with heat-mediated antigen retrieval in EDTA at pH 8.0 for paraffin sections (datasheet A05092-1). The selected placenta image used this retrieval, followed by 10% goat serum and 2 µg/mL primary antibody overnight at 4°C (datasheet A05092-1). If staining remains weak, compare two heating durations, such as 10 and 20 minutes, on adjacent sections while keeping detection conditions fixed (standard IHC practice). Record tissue preservation and nonspecific staining alongside signal strength, because harsher retrieval can damage morphology or increase background (standard IHC practice). Only then consider a citrate buffer at pH 6.0 as a fallback, validated against the EDTA condition on the same specimen (standard IHC practice).
Could fixation explain variable LNPEP staining between paraffin blocks?
The selected placenta caption identifies a paraffin section but does not report its fixative (datasheet A05092-1). Target-specific fixation sensitivity is therefore unknown; neither tissue staining patterns nor LNPEP topology establishes an optimal fixation condition (datasheet A05092-1; HPA tissue IHC; UniProt Q9UIQ6 topology). For prospective samples, standardize the fixative, tissue thickness and time before processing, and record those variables for each block (standard IHC practice). Compare adjacent sections using the same EDTA pH 8.0 retrieval and antibody conditions before attributing differences to biology (datasheet A05092-1; standard IHC practice). Include a consistently processed positive control, and assess morphology as well as staining in each run (standard IHC practice).
Should LNPEP appear at the membrane or in the cytoplasm?
Score membrane-associated and cytoplasmic staining separately: LNPEP resides in intracellular vesicles and can translocate to the cell surface in response to insulin or oxytocin (UniProt Q9UIQ6 subcellular location). HPA describes predominantly cytoplasmic tissue staining, while its subcellular summary lists membrane localization (HPA tissue IHC; HPA subcellular). The precursor spans the membrane at residues 111–131, with residues 1–110 cytoplasmic and 132–1025 extracellular (UniProt Q9UIQ6 topology). In brain, only the membrane-bound form is reported, although tissue staining may include vesicular signal (UniProt Q9UIQ6 subcellular location). Check whether an apparent membrane rim follows intact cell borders across the section before scoring it as membrane staining (standard IHC practice).
How can epitope position change what LNPEP staining means?
LNPEP has 3 annotated isoforms, and the supplied caption does not identify the catalog antibody's epitope (UniProt Q9UIQ6 isoforms; datasheet A05092-1). Its membrane-spanning segment is 111–131; residues 1–110 face the cytoplasm, whereas 132–1025 form the extracellular region (UniProt Q9UIQ6 topology). A pregnancy serum form begins at residue 155, so an antibody recognizing an amino-terminal sequence absent from that form would not detect it (UniProt Q9UIQ6 processing). The extracellular region contains annotated glycosylation sites, making epitope identity relevant when interpreting differences between specimens (UniProt Q9UIQ6 glycosylation; standard IHC practice). Obtain the immunogen or epitope specification before assigning staining to an isoform or processed form (standard IHC practice).
How should I assess LNPEP with a multiplex fluorescence experiment?
Treat multiplex IF as a separate assay because the supplied catalog evidence documents paraffin-section chromogenic IHC and gives no IF validation or IF fixation condition (datasheet A05092-1). Pair LNPEP with an independently validated marker for the expected cell type, such as glandular cells in appendix or duodenum, then inspect overlap within individual cells (HPA tissue IHC; standard IF practice). Choose well-separated fluorophores and favor a far-red channel when tissue autofluorescence obscures shorter wavelengths; inspect an unstained section before setting exposure (standard IF practice). Epitope position is unspecified, so compare permeabilized and nonpermeabilized conditions: residues 1–110 are cytoplasmic and 132–1025 extracellular (datasheet A05092-1; UniProt Q9UIQ6 topology). Verify each channel with single-label controls before interpreting colocalization (standard IF practice).
How do I distinguish LNPEP staining from chromogenic background?
First inspect a section processed without primary antibody to reveal secondary-reagent or chromogen signal (standard IHC practice). Use a peroxidase block before HRP detection and stop DAB development at a consistent endpoint across comparison sections (standard IHC practice). The selected placenta workflow used 10% goat serum, 2 µg/mL primary antibody overnight at 4°C, an HRP-linked secondary and DAB (datasheet A05092-1). If diffuse staining persists, compare shorter primary incubations or lower primary concentrations while retaining the same retrieval and control tissue (standard IHC practice). Do not automatically discard extracellular-looking signal: HPA reports additional plasma positivity in several tissues, and UniProt lists a secreted form (HPA tissue IHC; UniProt Q9UIQ6 processing).
What is a reproducible way to score LNPEP IHC? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and tissue compartment before scoring, and keep membrane-associated and cytoplasmic signal separate (UniProt Q9UIQ6 subcellular location; HPA tissue IHC; standard IHC practice). For each compartment, report the percentage of positive viable cells and an H-score: sum the percentages at intensity 0–3 multiplied by their intensity, giving 0–300 (standard IHC practice). Where cell counts vary, report positive cells per mm² of viable tissue and normalize comparisons to the same annotated cell population (standard IHC practice). Apply identical retrieval, staining, imaging and scoring thresholds to all comparison sections (standard IHC practice). Record the fraction of excluded damaged tissue so that changes in sample quality remain visible (standard IHC practice).
Which patterns support genuine LNPEP signal rather than artefact?
Look for staining in intact cells with a plausible vesicular, cytoplasmic or membrane-associated pattern, assessed against matched controls (UniProt Q9UIQ6 subcellular location; HPA tissue IHC; standard IHC practice). HPA reports high glandular-cell staining in appendix and duodenum, while its tissue reliability note reports low consistency with RNA expression, so treat those patterns as context rather than proof (HPA tissue IHC). Be cautious with signal confined to section edges, necrotic regions or areas that also stain without primary antibody (standard IHC practice). Assess endogenous peroxidase with the no-primary control before interpreting DAB deposits as LNPEP (standard IHC practice). Recheck unexpected nuclear-only staining or staining in a cell population absent from the intended analysis against morphology and an independently supported control (UniProt Q9UIQ6 subcellular location; standard IHC practice).
Boster reagents
Best LNPEP / Leucyl-cystinyl aminopeptidase IHC Antibodies
Validated LNPEP antibodies have IHC data from human placenta and mouse and rat brain paraffin sections, plus IF data from human lung tissue (catalog image captions).
Real IHC data
Anti-LNPEP Antibody ®
Cat # A05092-1
Real IF data
Anti-Leucyl-cystinyl aminopeptidase LNPEP Antibody
Cat # A05092
A05092-1 is listed for IHC in human, mouse and rat samples, with paraffin-section images from human placenta and mouse and rat brain (catalog applications, reactivity and image captions). A05092 is listed for human IF, with an image from human lung tissue (catalog applications, reactivity and image caption).
Which to pick: Choose A05092-1 for tissue IHC, including cross-species work, because IHC is listed for human, mouse and rat and its images show paraffin sections from all three species (catalog applications, reactivity and image captions). Its captions do not report the fixative, so the paraffin images do not establish fixation (A05092-1 image captions). Choose A05092 for human IF; ICC is not listed, and clone information is unreported for both SKUs (catalog applications, reactivity and clone fields). The selected A05092-1 tissue-IHC caption documents paraffin sections, but does not specify the fixative (selected-SKU IHC image A05092-1).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q9UIQ6 (LCAP_HUMAN, Leucyl-cystinyl aminopeptidase).
- Human Protein Atlas. LNPEP tissue IHC expression (reliability: Approved).
- Human Protein Atlas. LNPEP subcellular location (ICC-IF): Membrane.
- Human Protein Atlas. LNPEP antibody validation summary (1 antibodies).
- Leucyl and Cystinyl Aminopeptidase as a Prognostic-Related Biomarker in OV Correlating with Immune Infiltrates. Pharmacogenomics and personalized medicine 2023 — PMC10244028.
- Expression of Oxytocin/Neurophysin I and Oxytocinase in the Equine Conceptus from Day 8 to Day 21 Post-Ovulation. Animals : an open access journal from MDPI 2022 — PMC8996865.
- Characterization of serum and tissue oxytocinase and tissue oxytocin in the pregnant and non-pregnant mare. Scientific reports 2023 — PMC10030782.
- PubMed PMID:8550619 — UniProt-cited evidence.
- PubMed PMID:9177475 — UniProt-cited evidence.
- PubMed PMID:10759854 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for LNPEP (Leucyl-cystinyl aminopeptidase). Expected localisation Cytoplasmic staining in most tissues; some plasma positivity (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A05092-1). Validated IHC antibody: A05092-1 at 2-5 μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Appendix (Glandular cells); negative None in HPA (detected in all 45 tissues); use no-primary + isotype controls. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human placenta tissue; fixative not specified (datasheet A05092-1); 2. Fixation: Image fixative and duration unreported (datasheet A05092-1); 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 A05092-1); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A05092-1); 8. Primary antibody: Rabbit anti-LNPEP, 2-5 μg/ml (datasheet A05092-1); 9. Primary incubation: Overnight at 4 °C (datasheet A05092-1). Watch for: Fixation: Keep fixation consistent across sections. (standard IHC practice; not target-specific); Caveat: Secreted pregnancy serum form may add extracellular signal (UniProt); Isoform / epitope: 3 isoforms; cytoplasmic epitopes miss soluble form (UniProt); Regulation: Insulin/oxytocin shifts LNPEP to the surface (UniProt). Evidence: UniProt Q9UIQ6, HPA tissue IHC · Approved, HPA ICC-IF · Membrane, Datasheet A05092-1, PMC8996865, PMC10030782. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/LNPEP/immunohistochemistry-ihc-guide.