LL-37: Complete Research Guide — The Only Human Cathelicidin, Multi-Mechanism Wound Healing & Immunomodulation Data (2026)
- LL-37 (CAS: 154947-66-7; 37 amino acids; MW: ~4,493 Da) is the C-terminal antimicrobial fragment of hCAP-18 (human cationic antimicrobial protein 18), and the only cathelicidin found in humans. Encoded by the CAMP gene, it is expressed in neutrophils, macrophages, and epithelial cells of the skin, lung, GI tract, and urogenital tract as a component of the innate immune system.
- LL-37 operates through three mechanistically distinct pathways: (1) direct membrane disruption of bacterial, fungal, and viral pathogens via electrostatic interaction with negatively charged microbial membranes; (2) LPS neutralization by competitively blocking LPS interaction with TLR4/CD14, inhibiting downstream NF-κB p50/p65 nuclear translocation; (3) host cell receptor signaling via FPRL1 (formyl peptide receptor-like 1) and EGFR transactivation, stimulating cell migration, proliferation, and angiogenesis.
- Heilborn et al. (2003) published the foundational wound healing study documenting that hCAP-18/LL-37 is produced in human skin upon wounding, peaks at 48 hours post-injury in migrating epithelium, and is absent from chronic non-healing ulcers — establishing LL-37 deficiency as a mechanistic contributor to impaired wound healing (J Invest Dermatol, 2003 — PMID: 12603850).
- Koczulla et al. (2003) published the angiogenesis mechanism in Journal of Clinical Investigation: LL-37 stimulates collateral formation in a rabbit hind-limb ischemia model via FPRL1 on endothelial cells; CRAMP-deficient mice (lacking the murine LL-37 homolog) show decreased neovascularization of skin lesions (PMID: 12782669).
- Research-grade LL-37 is available in a 5mg configuration (Research Use Only) with batch-specific COAs through the YPB catalog.
- ~7,000 monthly US searches; the only endogenous antimicrobial peptide in the YPB catalog; uniquely positioned at the intersection of innate immunity, wound healing, and anti-infective research. Updated April 2026.
What Is LL-37 and Why Is It Unique Among Research Peptides?
Only Human Cathelicidin
3 Non-Overlapping Mechanisms
LL-37 (CAS: 154947-66-7; LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES; MW: ~4,493 Da) is the C-terminal 37-amino acid antimicrobial fragment of hCAP-18 (human cationic antimicrobial protein 18), the only cathelicidin encoded in the human genome. Updated April 2026. The human CAMP gene encodes hCAP-18 as a precursor; LL-37 is cleaved from the C-terminus of hCAP-18 by proteinase 3 (released from neutrophils during immune activation) and by other proteases at epithelial surfaces. The “LL” designation reflects the two leucine residues at the N-terminus; “37” designates its 37-amino acid length. Zanetti (2004) defined cathelicidins as “multifunctional peptides of the innate immunity,” and LL-37 is the canonical human example of this class (Zanetti, J Leukoc Biol, 2004).
LL-37 is expressed in neutrophils, macrophages, and epithelial cells of the skin, lung, GI tract, and urogenital tract. It is present in wound fluid, sweat, saliva, and breast milk. Its broad tissue distribution reflects its role as a first-line innate defense mechanism that operates before the adaptive immune response is activated — and its involvement in wound healing processes that are both antimicrobial and regenerative. This dual antimicrobial/regenerative profile makes LL-37 unique within the YPB catalog: no other compound simultaneously addresses pathogen membrane disruption, endotoxin neutralization, wound re-epithelialization, and angiogenesis through non-overlapping mechanisms.
Key Characteristics
| Parameter | Value |
|---|---|
| Full Sequence | LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES (37 amino acids) |
| Common Names | LL-37; hCAP-18 C-terminal fragment; human cathelicidin; CAP-18/LL-37; CAMP gene product |
| CAS Number | 154947-66-7 |
| Molecular Weight | ~4,493 Da |
| Amino Acids | 37 (C-terminal fragment of hCAP-18; cleaved by proteinase 3 and other proteases) |
| Half-Life | Short in plasma (<60 minutes); stabilized by serum protein binding at wound sites; activity retained at 50% serum in published studies |
| Structural Class | α-helical cationic antimicrobial peptide; amphiphilic helix; net positive charge (+6 at physiological pH) |
| Primary Mechanisms | (1) Membrane disruption (Gram+, Gram−, fungi, enveloped viruses); (2) LPS neutralization via TLR4/CD14 competitive inhibition; (3) FPRL1/EGFR receptor signaling → wound closure, angiogenesis, immune cell chemotaxis |
| Endogenous Expression | Neutrophils, macrophages, epithelial cells (skin, lung, GI, urogenital); wound fluid, sweat, saliva, breast milk |
| FDA Status | Not research-grade as a compound. Research Use Only (RUO). Topical LL-37 formulations in clinical development by third parties. |
| WADA Status | Not explicitly listed on WADA Prohibited List 2025; verify current list for AMP classifications |
| Storage | Lyophilized: −20°C. Reconstituted: 2–8°C, use within 14 days. Avoid metal-ion-containing buffers (LL-37 can chelate divalent cations which affect its structure) |
| Unique Position in YPB Catalog | Only endogenous antimicrobial peptide; only compound with direct bacterial membrane disruption activity in the catalog |
How Does LL-37 Work? Three Non-Overlapping Mechanisms
LL-37’s pharmacological complexity is what makes it both scientifically rich and uniquely valuable as a research tool. Three entirely separate mechanisms operate simultaneously in published research models.
Mechanism 1: Direct Membrane Disruption (Antimicrobial Activity)
LL-37 is a cationic (+6 net charge) amphiphilic α-helical peptide. Its antimicrobial mechanism relies on electrostatic attraction toward the negatively charged outer membrane surfaces of bacteria (lipopolysaccharide in Gram-negative, lipoteichoic acid/teichoic acid in Gram-positive), fungi (ergosterol-containing membranes), and enveloped viruses. Upon binding, LL-37 inserts its hydrophobic face into the microbial membrane bilayer, disrupting membrane integrity via carpet-like or toroidal-pore mechanisms, causing membrane depolarization, leakage of intracellular contents, and microbial cell death. Published data documents broad-spectrum activity against clinically relevant pathogens including Gram-negative bacteria (E. coli, P. aeruginosa), Gram-positive bacteria (S. aureus including MRSA), and fungi. Activity in published studies is maintained at 50% serum concentration, a key distinction from many synthetic antimicrobials.
Mechanism 2: LPS Neutralization and TLR4/NF-κB Modulation
Beyond direct killing, LL-37 binds lipopolysaccharide (LPS) with high affinity, competitively preventing LPS interaction with lipopolysaccharide-binding protein (LBP), co-receptor CD14, and the TLR4 receptor complex on immune cells. This LPS neutralization blocks the primary signal that drives septic inflammatory cascades in Gram-negative infections. Published data documents that LL-37 inhibits LPS-induced NF-κB p50/p65 nuclear translocation, completely inhibiting expression of certain pro-inflammatory genes (p50, TNFAIP2) and reducing expression of others (TNF-α) in stimulated macrophages and endothelial cells. This LPS-TLR4-NF-κB modulation mechanism is distinct from and complementary to KPV’s direct NF-κB inhibition — LL-37 prevents the inflammatory signal at the receptor level, while KPV blocks it at the transcription factor level.
Mechanism 3: FPRL1/EGFR Receptor Signaling (Wound Healing and Angiogenesis)
LL-37’s role in wound healing and tissue repair is mediated by G-protein-coupled receptor FPRL1 (formyl peptide receptor-like 1; also designated FPR2) and EGFR (epidermal growth factor receptor) transactivation. Koczulla et al. (2003) published the angiogenesis mechanism in Journal of Clinical Investigation: LL-37 stimulates new blood vessel formation in endothelial cells via FPRL1, demonstrated by collateral formation in a rabbit hind-limb ischemia model and reduced skin wound neovascularization in CRAMP-deficient mice (lacking the murine LL-37 homolog) (Koczulla et al., J Clin Invest, 2003 — PMID: 12782669). EGFR transactivation by LL-37 stimulates keratinocyte and epithelial cell migration, accelerating wound closure in published skin and airway epithelial models.
What Systems Has LL-37 Been Investigated For?
LL-37’s published research applications span wound healing, innate immunity, anti-infective models, inflammatory skin disorders, and angiogenesis research.
Wound Healing and Re-Epithelialization Research
Heilborn et al. (2003) published the defining wound healing study in Journal of Investigative Dermatology: hCAP-18/LL-37 is produced in human skin upon wounding, with expression peaking at 48 hours post-injury in the inflammatory infiltrate and in the migrating epithelium at the wound edge. Levels returned to pre-injury baseline upon wound closure. Critically, hCAP-18/LL-37 was absent from the epithelium of chronic non-healing ulcers — establishing LL-37 deficiency as a mechanistically relevant factor in impaired epithelial regeneration. Shaykhiev et al. (2005) confirmed that LL-37 stimulates airway epithelial cell proliferation and wound closure via FPRL1 and EGFR signaling (Shaykhiev et al., Am J Physiol Lung Cell Mol Physiol, 2005 — PMID: 15964896).
Angiogenesis Research
The Koczulla et al. (2003) Journal of Clinical Investigation paper established LL-37 as an angiogenic peptide: subcutaneous administration induced formation of new blood vessels in a rabbit hind-limb ischemia model, and CRAMP-deficient mice showed significantly reduced neovascularization in skin wounds compared to wild-type controls. This FPRL1-dependent angiogenesis mechanism is distinct from VEGF-mediated angiogenesis (the primary mechanism of BPC-157) and provides a separate pathway for studying neovascularization in wound healing and ischemia research contexts.
Innate Immunity and LPS Neutralization Research
LL-37’s LPS-binding activity has been extensively characterized as a model for endotoxin neutralization. Published data documents that LL-37 prevents LPS from binding to its receptor complex components (LBP, CD14, MD-2, TLR4), competitively inhibiting the upstream TLR4 signal before NF-κB activation occurs. This upstream LPS-neutralization mechanism is the basis for research interest in LL-37 for sepsis biology, endotoxemia models, and innate immune checkpoint research.
Psoriasis and Skin Inflammation Research
LL-37 plays a documented role in psoriasis pathogenesis: it forms complexes with self-DNA released from dying cells, which then activate plasmacytoid dendritic cells (pDCs) via TLR9, triggering interferon-α production. This mechanism of converting self-DNA into an autoimmune trigger is unique to LL-37 among the compounds in the YPB catalog and has positioned it as a research tool in psoriasis biology and autoimmune skin disorder research.
What Does the Human Research Data Show So Far?
| Study Type | Route/Model | N | Key Finding & Adverse Events | Year |
|---|---|---|---|---|
| In vivo human wound biology — Heilborn et al. | Human skin wound biopsies (observational) | Human skin samples (acute wounds + chronic ulcers) | hCAP-18 peaks at 48h in acute wounds in migrating epithelium; absent in chronic non-healing ulcers. Establishes LL-37 as endogenous wound healing component. No adverse event framework (observational). | 2003 |
| Phase 2 clinical trial (chronic venous leg ulcers) — third-party developer | Topical formulation | Small cohort (Phase 2) | Topical LL-37 studied for non-healing ulcers; preliminary data suggests improved wound closure rates. Full published results limited. No serious adverse events reported for topical route. | 2014–ongoing |
| Human antimicrobial expression data — multiple groups | Tissue expression (observational) | Multiple human tissue studies | LL-37 expression confirmed in wound fluid, sweat, saliva, breast milk, neutrophils, and multiple epithelial tissues — establishing robust endogenous biology relevance. | Various |
| Synthetic LL-37 human interventional RCT | N/A | No large-scale published RCT as of April 2026 | No published large-scale randomized controlled trial for synthetic LL-37 in human subjects as of April 2026. Third-party topical Phase 2 data limited in published form. | N/A |
How Does LL-37 Compare to Other Wound Healing and Anti-Infective Research Peptides?
| Parameter | LL-37 | BPC-157 | TB-500 | KPV |
|---|---|---|---|---|
| Primary Class | Endogenous cathelicidin AMP; innate immunity peptide | Synthetic gastric pentadecapeptide; tissue repair | Thymosin Beta-4; actin-binding protein | α-MSH C-terminal tripeptide; NF-κB inhibitor |
| Direct Antimicrobial Activity | Yes — membrane disruption (bacteria, fungi, enveloped viruses) | No direct antimicrobial activity | No direct antimicrobial activity | No direct antimicrobial activity |
| LPS Neutralization | Yes — TLR4/CD14 competitive inhibition upstream of NF-κB | No | No | No (KPV inhibits NF-κB downstream of TLR4) |
| Angiogenesis Mechanism | Yes — FPRL1 on endothelial cells (Koczulla 2003, PMID: 12782669) | Yes — VEGFR2/NO pathway (different receptor) | Indirect (supports cell migration to vascularized zones) | No primary angiogenesis activity |
| Wound Re-Epithelialization | Yes — FPRL1/EGFR transactivation (keratinocyte migration) | Yes — VEGFR2 vascular support | Yes — G-actin-mediated cell migration | No direct re-epithelialization mechanism |
| Endogenous Human Origin | Yes — naturally present in human neutrophils, epithelia, wound fluid | No (synthetic; derived from gastric BPC) | Yes (naturally present as Thymosin Beta-4) | No (synthetic fragment) |
| PubMed Publications | 500+ (LL-37 / hCAP-18) | 800+ | 400+ | 100+ |
| Research-Grade Available? | Yes — RUO | Yes — RUO | Yes — RUO | Yes — RUO |
Researchers studying wound healing at the innate immunity interface can combine LL-37 (antimicrobial + LPS-TLR4 + FPRL1 angiogenesis) with BPC-157 (VEGFR2/NO vascular repair) and TB-500 (cell migration) for a comprehensive four-mechanism wound biology protocol covering antimicrobial, endotoxin neutralization, angiogenesis (two independent pathways), and cell mobilization simultaneously. The GHK-Cu Research Guide covers the gene expression layer that can be added to this protocol for a five-compound wound healing research catalog.
What Should Researchers Know About LL-37 Stability and Handling?
LL-37 at ~4,493 Da is a large unstructured peptide in lyophilized form that adopts an α-helical conformation in hydrophobic environments or at interfaces. Its amphiphilic helical structure is critical for membrane activity and receptor binding.
Storage and Reconstitution Protocol
Lyophilized LL-37 is stable at −20°C for up to 24 months when protected from moisture and light. LL-37 is susceptible to aggregation in aqueous solution, particularly at concentrations above its critical aggregation concentration. Reconstitution in physiological saline or bacteriostatic water is standard; avoid metal-ion-rich buffers (phosphate buffered saline with heavy metals, or EDTA-free preparations) as divalent cations (Mg2+, Zn2+, Ca2+) at high concentrations can affect LL-37’s helical structure and membrane activity. Once reconstituted, solutions should be held at 2–8°C and used within 14 days. Avoid repeated freeze-thaw cycles which promote aggregation.
COA Verification
At ~4,493 Da, HPLC purity (≥95% or ≥98% depending on specification) combined with mass spectrometry confirmation of the full 37-residue sequence is the standard quality protocol. Due to LL-37’s tendency to self-associate at high concentrations, HPLC should be run under conditions that minimize aggregation (use of acetonitrile gradient with TFA modifier is standard). Endotoxin testing (<1 EU/mg) is particularly important for LL-37, as the compound is used in LPS biology and antimicrobial research — endotoxin contamination in the research sample would directly confound experimental results. All YPB LL-37 batches include lot-traceable COA documentation through the COA Library.
Key Research Findings: LL-37 in 2026
Key Research Findings
- Only human cathelicidin: LL-37 is the C-terminal fragment of hCAP-18, the only cathelicidin encoded in the human genome (CAMP gene) — unique endogenous status in the YPB catalog.
- Direct membrane disruption against bacteria, fungi, enveloped viruses: Cationic (+6) amphiphilic α-helix disrupts negatively charged microbial membranes; activity maintained at 50% serum concentration in published studies.
- LPS neutralization via TLR4/CD14 competitive inhibition: LL-37 binds LPS directly, preventing TLR4 receptor complex assembly, blocking NF-κB p50/p65 nuclear translocation upstream — distinct from KPV’s downstream NF-κB inhibition.
- Angiogenesis via FPRL1 confirmed in vivo (Koczulla 2003, PMID: 12782669): LL-37 stimulates collateral vessel formation in rabbit hind-limb ischemia; CRAMP-deficient mice show reduced wound neovascularization — confirming LL-37 as an endogenous angiogenic signal.
- Wound re-epithelialization confirmed in human tissue (Heilborn 2003, PMID: 12603850): hCAP-18/LL-37 peaks at 48h in migrating wound epithelium; absent from chronic non-healing ulcers — endogenous LL-37 deficiency as a wound healing mechanistic contributor.
- EGFR transactivation drives epithelial migration: LL-37 stimulates keratinocyte and airway epithelial proliferation and wound closure via FPRL1/EGFR in published cell culture and airway models (Shaykhiev et al. 2005, PMID: 15964896).
- Psoriasis pathogenesis mechanism identified: LL-37-self-DNA complexes activate pDC via TLR9 → IFN-α production — unique autoimmune biology application not shared by any other YPB compound.
- 500+ PubMed publications: Large evidence base spanning antimicrobial activity, wound healing, innate immunity, inflammation, and clinical research contexts.
Browse the Full Research Catalog
Market Demand and Research Interest
| Demand Indicator | LL-37 Data Point |
|---|---|
| Monthly US searches | ~7,000/mo |
| PubMed publications (total) | 500+ (LL-37 / hCAP-18 combined) |
| PubMed publications (2020+) | 100+ new publications since 2020 including wound healing, COVID-19 innate immunity, and cancer biology |
| Human wound biology data | Heilborn 2003 PMID: 12603850 — in vivo human wound tissue; hCAP-18 production confirmed in human wound re-epithelialization |
| Angiogenesis in vivo confirmation | Koczulla 2003 PMID: 12782669 — rabbit hind-limb ischemia model; CRAMP-KO mouse neovascularization confirmation |
| Unique catalog position | Only endogenous antimicrobial peptide; only compound with direct bacterial membrane disruption activity |
| Keyword difficulty range | Low competition (KD <15) |
How Can Researchers Offer LL-37 Under Their Own Brand?
LL-37 Wholesale Pricing & Margin Analysis
| SKU | Compound | Premier ($497/mo) | Core ($297/mo) | Suggested MSRP | Premier Margin |
|---|---|---|---|---|---|
| YPB.244 (RUO) | LL-37 5mg | $43.27 | $51.92 | $120.00 | $76.73 (64%) |
Use the YPB Profit Calculator to model projected revenue. LL-37 at Premier tier generates $76.73 gross margin per unit (64%). White-label brands offering LL-37 alongside BPC-157 and TB-500 create the most comprehensive wound healing research catalog in the market: direct antimicrobial + LPS neutralization (LL-37), VEGFR2/NO angiogenesis (BPC-157), and systemic cell migration (TB-500) — three non-overlapping wound healing mechanisms from a single buyer category. Download the full catalog for all wound healing SKU pricing.
Methodology & Data Sources
Methodology & Data Sources
Scientific literature: PubMed searched for “LL-37,” “hCAP-18,” “cathelicidin CAMP gene,” and CAS 154947-66-7. Search conducted through April 2026.
Key sources: Zanetti (2004) J Leukoc Biol (cathelicidin review); Heilborn et al. (2003) J Invest Dermatol (PMID: 12603850, wound re-epithelialization); Koczulla et al. (2003) J Clin Invest (PMID: 12782669, angiogenesis FPRL1); Shaykhiev et al. (2005) Am J Physiol (PMID: 15964896, airway wound closure); Dürr et al. (2006) Biochim Biophys Acta (only human cathelicidin review).
Limitations: No published large-scale RCT for synthetic LL-37 as a standalone injectable/SC compound. Third-party topical Phase 2 data is limited in published form. LL-37’s tendency to aggregate at high concentrations requires careful protocol design for in vitro experiments. This article is for educational purposes only.
References
- Zanetti, M. (2004). Cathelicidins, multifunctional peptides of the innate immunity. J Leukoc Biol, 75(1), 39–48.
- Heilborn, J. D., Nilsson, M. F., Kratz, G., Weber, G., Sørensen, O., Borregaard, N., & Ståhle-Bäckdahl, M. (2003). The cathelicidin anti-microbial peptide LL-37 is involved in re-epithelialization of human skin wounds and is lacking in chronic ulcer epithelium. J Invest Dermatol, 120(3), 379–389. PMID: 12603850
- Koczulla, R., von Degenfeld, G., Kupatt, C., Krötz, F., Zahler, S., Gloe, T., Issbruker, K., Onderka, J., Zaiou, M., Lebherz, C., Karl, A., Raake, P., Pfosser, A., Boekstegers, P., Welsch, U., Hiemstra, P. S., Vogelmeier, C., Gallo, R. L., Clauss, M., & Bals, R. (2003). An angiogenic role for the human peptide antibiotic LL-37/hCAP-18. J Clin Invest, 111(11), 1665–1672. PMID: 12782669
- Shaykhiev, R., Beisswenger, C., Kändler, K., Senske, J., Püchner, A., Damm, T., Behr, J., & Bals, R. (2005). Human endogenous antibiotic LL-37 stimulates airway epithelial cell proliferation and wound closure. Am J Physiol Lung Cell Mol Physiol, 289(5), L842–848. PMID: 15964896
- Dürr, U. H. N., Sudheendra, U. S., & Ramamoorthy, A. (2006). LL-37, the only human member of the cathelicidin family of antimicrobial peptides. Biochim Biophys Acta-Biomembr, 1758(9), 1408–1425.
- Yang, D., Chen, Q., Schmidt, A. P., Anderson, G. M., Wang, J. M., Wooters, J., Oppenheim, J. J., & Chertov, O. (2000). LL-37, the neutrophil granule- and epithelial cell-derived cathelicidin, utilizes formyl peptide receptor-like 1 (FPRL1) as a receptor to chemoattract human peripheral blood neutrophils, monocytes, and T cells. J Exp Med, 192(7), 1069–1074.
- Bowdish, D. M., Davidson, D. J., Speert, D. P., & Hancock, R. E. (2004). The human cationic peptide LL-37 induces activation of the extracellular signal-regulated kinase and p38 kinase pathways in primary human monocytes. J Immunol, 172(6), 3758–3765.
- Lande, R., Gregorio, J., Facchinetti, V., Chatterjea, D., Nguyen, H., & Gilliet, M. (2007). Plasmacytoid dendritic cells sense self-DNA coupled with antimicrobial peptide. Nature, 449(7162), 564–569. (LL-37-DNA complexes and psoriasis mechanism.)
- Vandamme, D., Landuyt, B., Luyten, W., & Schoofs, L. (2012). A comprehensive summary of LL-37, the factotum human cathelicidin peptide. Cell Immunol, 280(1), 22–35.
Frequently Asked Questions
LL-37 (CAS: 154947-66-7; 37 amino acids; ~4,493 Da) is the C-terminal fragment of hCAP-18, the only cathelicidin encoded in the human genome. Expressed by neutrophils, macrophages, and epithelial cells. In research models, published data demonstrates three non-overlapping mechanisms: (1) direct membrane disruption of bacteria, fungi, and enveloped viruses via cationic (+6) amphiphilic α-helical insertion; (2) LPS neutralization by competitive TLR4/CD14 complex inhibition, blocking NF-κB p50/p65 nuclear translocation; (3) FPRL1/EGFR receptor signaling stimulating angiogenesis (Koczulla et al. 2003, PMID: 12782669), wound re-epithelialization (Heilborn et al. 2003, PMID: 12603850), and immune cell chemotaxis. Not research-grade; Research Use Only (RUO). Updated April 2026.
BPC-157 promotes wound healing through VEGFR2/NO angiogenesis at the vascular level; TB-500 promotes healing through G-actin sequestration enabling systemic cell migration. Neither has direct antimicrobial activity, LPS neutralization capability, or FPRL1 receptor signaling. LL-37 contributes a fundamentally different set of mechanisms: killing pathogens in the wound environment, neutralizing their endotoxins before they trigger inflammatory cascades, and independently stimulating angiogenesis via a separate receptor (FPRL1) from BPC-157’s VEGFR2. For research on infected wound healing — where antimicrobial and tissue repair functions must be studied simultaneously — LL-37 addresses the antimicrobial and endotoxin-control dimensions that BPC-157 and TB-500 cannot. The three compounds together cover wound healing from four non-overlapping molecular angles.
Heilborn et al. (2003, PMID: 12603850) is the foundational study connecting LL-37 to wound re-epithelialization in human tissue. The key findings were: (1) hCAP-18/LL-37 production increases dramatically in human skin upon wounding, peaking at 48 hours post-injury in the inflammatory infiltrate and in the epithelium migrating across the wound bed; (2) levels return to baseline when the wound closes; (3) hCAP-18/LL-37 is absent from the epithelium of chronic non-healing ulcers. This third finding — absence from non-supports tissue health and recovery*s — established LL-37 deficiency as a mechanistically plausible contributor to impaired wound healing and provided the rationale for using exogenous synthetic LL-37 as a wound biology research tool to replace or supplement the deficient endogenous peptide.
LL-37 has two specific handling considerations. First, it tends to self-associate and aggregate at high concentrations in aqueous solution — reconstitution should be done at the lowest practical concentration and aggregation should be checked before use (clear solution is expected; opalescence or particulates indicate aggregation). Second, avoid metal-ion-rich buffers: divalent cations (Mg2+, Zn2+, Ca2+) at high concentrations affect LL-37’s α-helical structure and membrane activity. Reconstitute with bacteriostatic water rather than phosphate buffers containing heavy metals. Lyophilized material is stable at −20°C for 24 months; reconstituted solutions should be held at 2–8°C and used within 14 days without repeated freeze-thaw cycles. Endotoxin testing is particularly important for LL-37 given its use in LPS biology research.
Human evidence for LL-37 exists at two levels. First, endogenous LL-37 biology in human tissue is well-documented: Heilborn et al. (2003) published human wound biopsy data confirming hCAP-18/LL-37 expression kinetics in acute wounds and absence from chronic ulcers; multiple groups have confirmed expression in human neutrophils, epithelia, wound fluid, sweat, and breast milk. Second, a third-party clinical program studied topical LL-37 for chronic venous leg ulcers in Phase 2 trials, with preliminary published data suggesting improved wound closure rates and no serious adverse events. No published large-scale RCT for synthetic LL-37 as an injectable compound exists as of April 2026. All YPB LL-37 is Research Use Only.
Yes. YourPeptideBrand.com provides white-label dropship for LL-37 in a 5mg configuration at $43.27 Premier wholesale, with a suggested MSRP of $120 generating $76.73 gross margin per unit (64% margin). White-label storefronts include pre-built RUO-compliant product pages with molecular data tables, three-mechanism descriptions, handling precautions, and COA library links. Storefronts launch within 30 days with no inventory requirements. Use the profit calculator to model projected revenue.
Every LL-37 batch includes a lot-specific COA from an independent third-party laboratory: HPLC purity (≥95% to ≥98% per batch specification), MS confirmation of the full 37-residue sequence at ~4,493 Da, endotoxin (<1 EU/mg — particularly important for LPS biology research contexts), TAMC, and TYMC. The endotoxin specification is a critical quality parameter for LL-37, as endotoxin contamination in research-grade LL-37 would directly confound experiments studying LPS-TLR4 biology. All lots are traceable through the COA Library.
Premier tier members ($497/mo) access LL-37 5mg at $43.27 wholesale, generating $76.73 gross margin per unit at the $120 MSRP (64% margin). Core tier ($297/mo) pricing is $51.92. White-label brands offering a comprehensive wound healing research catalog — LL-37 ($76.73) + BPC-157 10mg ($64.77) + TB-500 10mg ($89.14) + GHK-Cu 100mg ($92.96) — generate $323.60 combined margin per four-compound wound healing research order at Premier tier. The LL-37 guide content is entirely differentiated from all other wound healing guides by its antimicrobial, endotoxin-neutralization, and FPRL1 angiogenesis mechanisms — no content overlap with any other YPB article.
Key Takeaways
Research Takeaways
- Only human cathelicidin: LL-37 is encoded by the sole human cathelicidin gene (CAMP); expressed in neutrophils, epithelia, wound fluid — unique endogenous standing in the YPB catalog.
- Three non-overlapping mechanisms: Membrane disruption (antimicrobial), LPS/TLR4 neutralization (endotoxin), FPRL1/EGFR signaling (wound closure, angiogenesis) — no single mechanism is shared with any other YPB compound.
- FPRL1 angiogenesis confirmed in vivo (Koczulla 2003, PMID: 12782669): Collateral formation in rabbit hind-limb ischemia; CRAMP-KO mouse neovascularization deficiency — LL-37 as an endogenous angiogenic signal independent of VEGF/BPC-157 pathway.
- Wound re-epithelialization in human tissue (Heilborn 2003, PMID: 12603850): 48h peak in migrating wound epithelium; absent in chronic non-healing ulcers — LL-37 deficiency as a mechanistic wound healing contributor.
- LPS neutralization upstream of NF-κB: Prevents TLR4/CD14 activation by LPS; distinct from KPV’s downstream NF-κB inhibition — the two compounds address the same inflammatory axis at different points.
- Aggregation at high concentrations: Unique handling consideration requiring low-concentration reconstitution and avoidance of divalent-cation-rich buffers.
- Endotoxin specification is critical: Endotoxin contamination in LL-37 directly confounds LPS biology experiments; strict <1 EU/mg standard essential.
Business Takeaways
- $76.73 gross margin per unit at Premier tier (64%) — strong margin with entirely unique three-mechanism narrative in the catalog.
- ~7,000 monthly searches at low KD — unique audience at the intersection of antimicrobial, wound healing, and innate immunity research.
- Zero content overlap with any other YPB guide — antimicrobial + LPS neutralization + FPRL1 angiogenesis is mechanistically distinct from BPC-157, TB-500, GHK-Cu, and KPV.
- Four-compound wound healing catalog (LL-37 + BPC-157 + TB-500 + GHK-Cu) generates $323+ combined margin per comprehensive wound healing research order at Premier tier.
Ready to add LL-37 to your research catalog? Book a consultation with the YPB team.
[ypb_studies peptide=”ll-37″]