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KLK1 / Kallikrein-1 · IHC design guide
Design Immunohistochemistry for KLK1
Plan KLK1 IHC in paraffin sections using salivary glandular and pancreatic exocrine staining as tissue references (HPA tissue IHC). Compare staining with appropriate controls, keeping in mind that secreted protein may appear away from its producing cells (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
KLK1 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 | Tissue staining compartment is not established (HPA tissue IHC) | |
| Staining pattern | Salivary glandular and pancreatic exocrine cells; site unreported (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen) | |
| Positive control | Adrenal gland+4 more · see all | |
| Negative control | Adipose tissue+4 more · see all |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation consistent across sections (standard IHC practice; not target-specific) | |
| Caveat | Secreted protein may stain away from producing cells (HPA tissue IHC) | |
| Regulation | Expression regulation is not specified (UniProt) | |
| Isoform / epitope | 2 isoforms; mature chain starts at residue 25—check the epitope (UniProt) |
Section 1
Recommended KLK1 IHC & IF Protocols
The catalog antibody’s IHC-P protocol (datasheet) is accompanied by four published KLK1 IHC protocols (PMC4521496; PMC12622486; PMC11432477; PMC8110393).
| Sample | Tissue sections; selected-image fixative not specified (standard IHC workflow) |
| Fixation | Image fixative and duration unreported (datasheet PA1625); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat-induced epitope retrieval in citrate buffer, pH 6.0, 20 min at 95–98 °C (standard rule: cytoplasmic / membrane antigen) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% normal serum of the secondary host, 30 min, room temperature (standard) |
| Primary antibody | Rabbit anti-KLK1, 0.5-1μg/ml (datasheet PA1625) |
| 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 | KLK1-positive staining in glandular cells of adrenal gland (HPA tissue IHC: Medium). HPA tissue profile: Expressed mainly in salivary gland but also pancreas. No signal in the no-primary control. |
💡Decision noteStart with citrate pH 6.0 retrieval at 95–98 °C for 20 min (page antigen-retrieval rule); the cited articles do not specify retrieval conditions.
Section 2
What Is the Expected KLK1 Staining Pattern?
Secreted KLK1 (HPA; UniProt P06870: no TM) stains salivary glandular cells (HPA: Medium; Approved).
| Salivary glandular cells stain at medium intensity (HPA). | Expected; pancreatic exocrine glandular cells also stain at medium intensity (HPA). |
| Strong nuclear staining (HPA: secreted). | Inconsistent with the secreted annotation; investigate artefact (HPA subcellular). |
| Adipocytes stain (HPA: Not detected). | Consider cross-reactivity or endogenous detection activity (HPA; general IHC practice). |
| Diffuse staining across cell types (HPA: glandular pattern). | Suggests background; check a no-primary control (HPA; general IHC practice). |
| No salivary glandular staining (HPA: Medium). | Unexpected; check the positive control, retrieval and detection (HPA; general IHC practice). |
💡Expected KLK1 appearancePositive: medium salivary glandular staining; nuclear or adipocyte signal is suspect (HPA).
| Secreted protein; no TM segment (HPA; UniProt P06870). | A strong nuclear pattern conflicts with the reported localization (HPA subcellular). |
| Signal 1–18; mature chain 25–262 (UniProt P06870). | The antibody epitope is unspecified; processing matters when assessing its location (UniProt P06870). |
| 2 isoforms (UniProt P06870). | Isoform 2 occurs in pancreas and salivary glands; antibody coverage is unknown (UniProt P06870). |
| IHC Approved; low staining–RNA consistency (HPA). | HPA notes secreted protein and disregards presumed off-target binding (HPA). |
| Situation | Likely cause | Next action |
|---|---|---|
| No salivary gland signal (HPA: Medium). | Possible assay failure (general IHC practice). | Check positive control, retrieval, dilution and detection (general IHC practice). |
| Strong nuclear signal (HPA: secreted). | Pattern conflicts with the secreted annotation (HPA subcellular). | Inspect a no-primary control and chromogen deposits (general IHC practice). |
| Adipocytes stain (HPA: Not detected). | Possible off-target binding or endogenous activity (HPA; general IHC practice). | Compare no-primary and salivary positive controls (HPA; general IHC practice). |
| Diffuse brown background (general IHC practice). | Possible endogenous activity or nonspecific binding (general IHC practice). | Check no-primary control; optimize blocking and washes (general IHC practice). |
| Weak kidney tubule staining (HPA: Low). | Kidney tubules show low staining (HPA). | Check salivary gland as a stronger positive tissue (HPA: Medium). |
| What should IF/ICC show? | No ICC-IF images or resolved main location are available (HPA subcellular). | Use the separate IF/ICC guide; do not assign an intracellular pattern (HPA subcellular). |
Experiment evidence
IHC & IF images showing KLK1 staining
PA1625 · IHCAnti-Kallikrein 1 antibody, PA1625, IHC(P) IHC(P): Human Pancreatic Cancer Tissue
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000167748-KLK1/tissue/cerebral+cortex#imid_16484619
HPA · Salivary glandHuman Protein Atlas IHC, Salivary gland. Source: https://www.proteinatlas.org/ENSG00000167748-KLK1/tissue/salivary+gland#imid_16484583
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000167748-KLK1/tissue/colon#imid_16484561
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000167748-KLK1/tissue/liver#imid_16484546
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for KLK1 IHC & IF
🧪Run pancreas first and expect staining in exocrine glandular cells (HPA: Medium in pancreatic exocrine glandular cells). Use adipose tissue adipocytes as the negative comparator (HPA: Not detected in adipocytes); on the pancreas slide, stromal cells should show only background rather than the glandular staining pattern (HPA: Medium in pancreatic exocrine glandular cells; standard IHC control practice).
Positive control tissue: Adrenal gland (Glandular cells, HPA Medium)
Negative control tissue: Adipose tissue (HPA Not detected)
ICC-IF cell lines (HPA subcellular resource): HPA carries no ICC-IF cell line for KLK1; 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: Include no-primary (secondary-only) and primary-matched host-species and immunoglobulin-class controls, matching clonality where applicable; use KLK1-knockout material or a validated peptide-block control if available (standard IHC control practice). Quench endogenous peroxidase for chromogenic detection and inspect the pancreas control for residual background (standard IHC practice).
⚠️Feasibility: A KLK1-specific fixation window and retrieval effect are unreported in the supplied evidence; the PA1625 IHC(P) pancreatic cancer caption does not report a fixative (selected hero caption: fixative not stated). The supplied evidence does not establish that frozen sections or IF/ICC are easier than paraffin IHC (HPA subcellular: no ICC-IF image cell lines). Because KLK1 is secreted, interpret luminal or extracellular staining cautiously and score the exocrine cell pattern against controls (HPA subcellular: Secreted; UniProt P06870: signal peptide 1–18; HPA: Medium in pancreatic exocrine glandular cells).
HPA tissue IHC evidence for KLK1
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Approved — Low consistency between antibody staining and RNA expression data. Secreted protein, tissue location of RNA and protein is expected to differ. Presumed off target binding observed and disregarded.). 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 | Medium | Protein (IHC) | HPA → |
| Appendix | Glandular cells | Medium | Protein (IHC) | HPA → |
| Colon | Glandular cells | Medium | Protein (IHC) | HPA → |
| Pancreas | Exocrine glandular cells | Medium | Protein (IHC) | HPA → |
| Rectum | 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 → |
| Bone marrow | Hematopoietic cells | Not detected | Protein (IHC) | HPA → |
| Breast | Adipocytes | Not detected | Protein (IHC) | HPA → |
| Caudate | Glial cells | Not detected | Protein (IHC) | HPA → |
| Cerebral cortex | Endothelial cells | Not detected | Protein (IHC) | HPA → |
Section 3
Advanced KLK1 IHC Tips
Troubleshoot KLK1 staining in paraffin sections by checking retrieval, controls, compartment, and scoring before interpreting chromogenic signal (HPA tissue IHC; UniProt P06870).
How should I adjust retrieval when KLK1 staining is weak in paraffin sections?
Start with citrate pH 6.0 HIER at 95–98 °C for 20 min in paraffin sections (page retrieval protocol). Run salivary gland or pancreas alongside the study section to distinguish weak retrieval from a genuinely low signal (HPA: KLK1 is expressed mainly in salivary gland and also pancreas). If both control and study sections are weak, check heating, cooling, and section attachment before changing retrieval conditions (standard IHC practice). Compare any adjusted retrieval on adjacent sections with the same antibody dilution and detection time, because stronger staining alone does not establish KLK1 specificity (standard IHC practice).
Could fixation explain loss of KLK1 staining?
KLK1-specific fixation sensitivity is unknown from the supplied evidence; the PA1625 tissue-IHC caption identifies pancreatic cancer tissue and IHC(P) but does not state a fixative (PA1625 caption). Record fixative, fixation duration, and processing history for each paraffin block, then compare sections using identical retrieval and detection conditions (standard IHC practice). If archival blocks vary, include a consistently processed salivary gland or pancreas control with each run (HPA: tissue IHC profile). A difference between blocks can support a processing hypothesis, but cannot establish a KLK1-specific fixation effect without a controlled fixation comparison (standard IHC practice).
Where should KLK1 signal appear, and when is compartment staining suspicious?
Interpret KLK1 as a secreted protein with no annotated transmembrane segment, rather than expecting a stable membrane rim (HPA: secreted; UniProt P06870 topology). Glandular staining in salivary gland and exocrine glandular staining in pancreas fit the reported tissue pattern (HPA: tissue IHC). Inspect epithelial cells and nearby luminal material separately, since a secreted antigen can appear beyond its producer cell (HPA: secreted; standard IHC interpretation). A strong nuclear-only pattern deserves scrutiny because neither the supplied subcellular evidence nor the processing record supports nuclear residence (HPA: secreted; UniProt P06870 processing).
Can processing or isoforms change what the antibody detects?
Map the antibody epitope before interpreting a negative section: KLK1 has a signal peptide at residues 1–18, a propeptide at 19–24, and a mature chain at 25–262 (UniProt P06870 processing). An epitope confined to a removed segment could behave differently from one retained in mature KLK1, although the supplied antibody caption does not identify its epitope (UniProt P06870 processing; PA1625 caption). KLK1 has 2 isoforms, and isoform 2 is reported in several tissues including pancreas and salivary glands (UniProt P06870). Compare the vendor-supplied epitope sequence with isoform sequences, and treat staining as isoform-agnostic until that comparison is possible (standard antibody validation practice).
How can I adapt this KLK1 question to multiplex IF?
For a separate IF experiment, pair KLK1 with a validated marker of glandular or exocrine glandular cells and inspect each channel independently before assessing overlap (HPA: salivary gland glandular cells; pancreas exocrine glandular cells). Choose fluorophores after imaging unstained tissue, placing the weaker channel away from its strongest autofluorescence and checking single-stain controls for bleed-through (standard IF practice). KLK1 lacks a transmembrane segment and is secreted, so choose permeabilisation according to the antibody's mapped epitope and whether intracellular antigen is being sought (UniProt P06870 topology; HPA: secreted). The PA1625 caption documents IHC(P), so establish IF performance independently rather than transferring its tissue image or fixation assumptions (PA1625 caption).
What should I check when KLK1 chromogen appears throughout the section?
Run a no-primary control and inspect the section before chromogen development to separate detection background from tissue pigment (standard chromogenic IHC practice). Include a peroxidase block when using a peroxidase-based detection system, and compare matched development times across sections (standard chromogenic IHC practice). Titrate the primary antibody and review blocking and wash steps if diffuse signal persists, keeping salivary gland or pancreas as an expected-positive reference (HPA: tissue IHC profile; standard IHC practice). Adipocytes in adipose tissue were reported as not detected, but the HPA record also notes presumed off-target binding, so evaluate any unexpected staining by cell type and morphology (HPA: tissue IHC).
How should I score KLK1 staining across sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the region of interest and cell class before scoring, because reported KLK1 staining differs among glandular cells, kidney tubules, and other sampled cells (HPA: tissue IHC). For cellular staining, report the percentage of positive target cells and an H-score using intensity grades 0–3, with a maximum of 300 (standard IHC scoring practice). For luminal or diffuse deposits, measure positive area per mm² separately from cell counts, since KLK1 is secreted (HPA: subcellular summary; standard image analysis practice). Normalize to eligible target-cell number or analyzable tissue area, and apply one threshold, retrieval condition, and chromogen development time across comparisons (standard IHC practice).
How can I distinguish a true KLK1-positive pattern from artefact?
Prioritize reproducible glandular or exocrine glandular staining in the appropriate morphology: salivary gland and pancreas are reported expression sites (HPA: tissue IHC). Check whether signal follows viable cells or plausible secreted material, while treating nuclear-only staining as unsupported by the supplied localisation evidence (HPA: secreted; UniProt P06870 topology). Discount staining restricted to section edges, folds, or necrotic regions, and investigate any signal reproduced in a no-primary control or after omitted peroxidase block (standard chromogenic IHC practice). HPA rates its KLK1 tissue IHC as Approved but reports low staining–RNA consistency and presumed off-target binding, so corroborate unexpected patterns with an independent specificity control (HPA: reliability description).
Boster reagents
Best KLK1 / Kallikrein-1 IHC Antibodies
PA1625 has real IHC(P) data from human pancreatic cancer tissue and lists human, mouse, and rat reactivity (PA1625 image caption; catalog PA1625). No IF data are supplied (catalog PA1625).
Real IHC data
Anti-Kallikrein 1/KLK1 Antibody ®
Cat # PA1625
PA1625 is listed for IHC and WB, with human, mouse, and rat reactivity (catalog PA1625). Its IHC(P) image shows human pancreatic cancer tissue; no IF image is supplied (PA1625 image caption; catalog PA1625).
Which to pick: Choose PA1625 for paraffin-section tissue IHC: its own image shows human pancreatic cancer tissue, and the listed human IHC dilution is 0.5–1 μg/ml; the fixative is unreported (PA1625 image caption; datasheet). No IF/ICC choice is supported because PA1625 lists only IHC and WB and supplies no IF data (catalog PA1625). For cross-species work, PA1625 lists human, mouse, and rat reactivity, but its IHC image documents human tissue only; clonality is unreported (catalog PA1625; PA1625 image caption).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P06870 (KLK1_HUMAN, Kallikrein-1).
- Human Protein Atlas. KLK1 tissue IHC expression (reliability: Approved).
- Human Protein Atlas. KLK1 subcellular location (ICC-IF): Secreted.
- Human Protein Atlas. KLK1 antibody validation summary (1 antibodies).
- Prognostic significance of multiple kallikreins in high-grade astrocytoma. BMC cancer 2015 — PMC4521496.
- KLK1 as an Epithelial-Specific Brake Inhibits Colorectal Tumorigenesis by Suppressing B1R-Mediated Fibroblast Phenotypic Transition. Advanced science (Weinheim, Baden-Wurttemberg, Germany) 2025 — PMC12622486.
- Tissue Kallikrein-1 Suppresses Type I Interferon Responses and Reduces Depressive-Like Behavior in the MRL/lpr Lupus-Prone Mouse Model. International journal of molecular sciences 2024 — PMC11432477.
- Human Tissue Kallikrein 1 Is Downregulated in Elderly Human Prostates and Possesses Potential In Vitro Antioxidative and Antifibrotic Effects in Rodent Prostates. Oxidative medicine and cellular longevity 2021 — PMC8110393.
- PubMed PMID:3004571 — UniProt-cited evidence.
- PubMed PMID:2898948 — UniProt-cited evidence.
- PubMed PMID:2686621 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for KLK1 (Kallikrein-1). Expected localisation Tissue staining compartment is not established (HPA tissue IHC). Antigen retrieval: Citrate pH 6.0 HIER, 95–98 °C, 20 min (rule: cytoplasmic / membrane antigen). Validated IHC antibody: PA1625 at 0.5-1μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Adrenal gland (Glandular cells); negative Adipose tissue. IHC workflow; specimen preparation unspecified. Protocol steps: 1. Sample: Tissue sections; selected-image fixative not specified (standard IHC workflow); 2. Fixation: Image fixative and duration unreported (datasheet PA1625); verify before use.; 3. Sectioning: 4–5 µm sections on charged slides (standard); 4. Deparaffinisation: Xylene, graded ethanol series to water (standard); 5. Antigen retrieval: Heat-induced epitope retrieval in citrate buffer, pH 6.0 , 20 min at 95–98 °C…; 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% normal serum of the secondary host, 30 min , room temperature (standard); 8. Primary antibody: Rabbit anti-KLK1, 0.5-1μg/ml (datasheet PA1625); 9. Primary incubation: Overnight at 4 °C (standard). Watch for: Fixation: Keep fixation consistent across sections (standard IHC practice; not target-specific); Caveat: Secreted protein may stain away from producing cells (HPA tissue IHC); Isoform / epitope: 2 isoforms; mature chain starts at residue 25—check the epitope (UniProt); Regulation: Expression regulation is not specified (UniProt). Evidence: UniProt P06870, HPA tissue IHC · Approved, HPA ICC-IF · Secreted, Datasheet PA1625, PMC4521496, PMC12622486. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/KLK1/immunohistochemistry-ihc-guide.