Overview
LL-37 is classified as a antimicrobial peptide peptide. Broad-spectrum antimicrobial, anti-biofilm, wound healing, immune modulation, anti-inflammatory.
The only human cathelicidin antimicrobial peptide. LL-37 is a 37-amino acid cationic peptide that directly disrupts microbial membranes (bacteria, viruses, fungi) and neutralizes bacterial endotoxins (LPS). Beyond direct antimicrobial action, LL-37 modulates innate immunity by chemoattracting neutrophils, monocytes, and T-cells to infection sites. Promotes wound healing via EGFR-mediated keratinocyte migration and angiogenesis. Demonstrates potent anti-biofilm properties against resistant organisms.
Also known as: Cathelicidin, CAP-18, hCAP-18
Category
Antimicrobial Peptide
Half-Life
4h
Route
SubQ
FDA Status
Not Approved
How Does LL-37 Work?
The only human cathelicidin antimicrobial peptide. LL-37 is a 37-amino acid cationic peptide that directly disrupts microbial membranes (bacteria, viruses, fungi) and neutralizes bacterial endotoxins (LPS). Beyond direct antimicrobial action, LL-37 modulates innate immunity by chemoattracting neutrophils, monocytes, and T-cells to infection sites. Promotes wound healing via EGFR-mediated keratinocyte migration and angiogenesis. Demonstrates potent anti-biofilm properties against resistant organisms.
At the molecular level, LL-37 operates through pathways characteristic of the Antimicrobial Peptide class, interacting with target receptors and downstream signaling cascades to produce its observed effects.
Published Research
The following studies are indexed from PubMed and peer-reviewed journals:
[1]LL-37 broad-spectrum antimicrobial and immunomodulatory effects
Comprehensive review of LL-37's dual antimicrobial and immunomodulatory functions, including membrane disruption, chemotaxis, cytokine regulation, and wound healing promotion.
Evidence: moderate[2]LL-37 anti-biofilm activity against resistant pathogens
Overhage et al.: LL-37 inhibits biofilm formation by Pseudomonas aeruginosa at sub-MIC concentrations, affecting bacterial attachment, migration, and quorum sensing.
Evidence: preclinical[3]LL-37 promotes wound healing via EGFR transactivation
Tokumaru et al.: LL-37 promotes wound re-epithelialization by stimulating keratinocyte migration through EGFR transactivation, providing mechanistic basis for wound-healing applications.
Evidence: preclinical[4]Cathelicidin deficiency increases susceptibility to infection
Chromek et al.: Studies in CAMP-knockout models demonstrate that cathelicidin deficiency significantly increases susceptibility to urinary tract and skin infections, validating LL-37's critical role in host defense.
Evidence: preclinical[5]LL-37 in chronic inflammatory conditions and immune regulation
Kahlenberg et al.: Review of LL-37's role in autoimmune and chronic inflammatory conditions including psoriasis, lupus, and rosacea. LL-37 acts as a danger signal activating dendritic cells and driving type I interferon production.
Evidence: moderate[6]Vitamin D-inducible antimicrobial peptide LL-37 binds SARS-CoV-2 Spike and accessory proteins ORF7a and ORF8.
A study published in Frontiers in cellular and infection microbiology investigating the effects and mechanisms.
Evidence: preclinical[7]Antimicrobial peptide LL-37 and its pro-form, hCAP18, in desquamated epithelial cells of human whole saliva.
A study published in European journal of oral sciences investigating the effects and mechanisms.
Evidence: moderate[8]Insight into the Mechanism of Interactions between the LL-37 Peptide and Model Membranes of Legionella gormanii Bacteria.
A study published in International journal of molecular sciences investigating the effects and mechanisms.
Evidence: preclinical[9]The Antimicrobial Peptide LL-37 as a Predictor Biomarker for Periodontitis with the Presence and Absence of Smoking: A Case-Control Study.
A study published in BioMed research international investigating the effects and mechanisms.
Evidence: anecdotal[10]Antimicrobial peptide CRAMP/LL-37 mediates ferroptosis resistance in cardiomyocytes by inhibiting cathepsin L.
A study published in Basic research in cardiology investigating the effects and mechanisms.
Evidence: preclinical[11]Cathelicidin peptide LL-37: A multifunctional peptide involved in heart disease.
A study published in Pharmacological research investigating the effects and mechanisms.
Evidence: preclinical[12]The roles of cathelicidin LL-37 in immune defences and novel clinical applications.
A study published in Current opinion in hematology investigating the effects and mechanisms.
Evidence: moderate[13]Associations of Serum Antimicrobial Peptide LL-37 with Longitudinal Cognitive Decline and Neurodegeneration Among Older Adults with Memory Complaints.
A study published in Journal of Alzheimer's disease : JAD investigating the effects and mechanisms.
Evidence: preclinical[14]Synergistic effect of antimicrobial peptide LL-37 and colistin combination against multidrug-resistant Escherichia coli isolates.
A study published in Future microbiology investigating the effects and mechanisms.
Evidence: preclinical[15]Evaluation of LL-37 antimicrobial peptide derivatives alone and in combination with vancomycin against S. aureus.
A study published in The Journal of antibiotics investigating the effects and mechanisms.
Evidence: preclinical[16]Roles and Mechanisms of Human Cathelicidin LL-37 in Cancer.
A study published in Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology investigating the effects and mechanisms.
Evidence: moderate[17]Cathelicidin LL-37 peptide regulates endothelial cell stiffness and endothelial barrier permeability.
A study published in American journal of physiology. Cell physiology investigating the effects and mechanisms.
Evidence: preclinical[18]Acute salivary antimicrobial peptide secretion response to different exercise intensities and durations.
A study published in American journal of physiology. Regulatory, integrative and comparative physiology investigating the effects and mechanisms.
Evidence: preclinical[19]Antifungal properties of cathelicidin LL-37: current knowledge and future research directions.
A study published in World journal of microbiology & biotechnology investigating the effects and mechanisms.
Evidence: preclinical[20]Smoking reduces cathelicidin LL-37 and human neutrophil peptide 1-3 levels in the gingival crevicular fluid of patients with periodontitis.
A study published in Journal of periodontology investigating the effects and mechanisms.
Evidence: moderateSafety Profile
Endogenous human peptide with well-characterized biology. Cytotoxic to eukaryotic cells at high concentrations (>25mcg/mL). Concentration-dependent effects: low doses immunomodulatory, high doses cytotoxic. Growing research interest in CIRS/mold illness protocols. Not FDA-approved as a therapeutic.
| Side Effect | Incidence | Severity |
|---|---|---|
| Injection site reaction (redness, swelling) | ~15% of users | mild |
| Flu-like symptoms (immune activation) | ~10% of users | mild |
| Mild fever | ~5% of users | mild |
| Fatigue | ~8% of users | mild |
Sourcing LL-37 for Research
If you're looking to source LL-37 for laboratory research, our vendor directory compares pricing, purity testing, and COA verification from independently vetted suppliers.
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Full Research Profile
LL-37 — dosing, interactions, timelines & more
Comprehensive compound profile with sourcing information, stacking synergies, and outcome timelines.