LL-37 is the only known human cathelicidin antimicrobial peptide. It is a 37 amino acid fragment of hCAP18, produced by neutrophils, epithelial cells, and macrophages as a first-line innate immune defence.

How does LL-37 kill bacteria?

LL-37 disrupts bacterial membranes through electrostatic interaction with negatively charged lipid bilayers. It also neutralises endotoxins (LPS), prevents biofilm formation, and modulates downstream immune signalling via TLR pathways.

Can LL-37 be used topically?

Yes. LL-37 is researched in both subcutaneous and topical formulations. Topical application is studied for chronic wound healing, infected ulcers, and biofilm disruption on wound surfaces.

What is the difference between LL-37 and other antimicrobial peptides?

LL-37 is the only cathelicidin produced by the human body, giving it unique immunomodulatory properties beyond simple antimicrobial activity. It modulates TLR signalling, promotes angiogenesis, and recruits immune cells - functions synthetic antimicrobial peptides typically lack.

Can bacteria develop resistance to LL-37?

Resistance is much harder to evolve against membrane-targeting peptides than against receptor- or enzyme-targeting antibiotics, because there is no single protein for the pathogen to mutate. Some bacteria modify their outer membrane charge to reduce electrostatic attraction, but full escape is rare. That is part of why antimicrobial peptides like LL-37 are such a hot research area in the antibiotic-resistance era.

What is the vitamin D connection?

Cathelicidin (CAMP) gene expression is directly regulated by the vitamin D receptor. Calcitriol (the active form of vitamin D) upregulates endogenous LL-37 production, which is one of the mechanisms behind the observed relationship between vitamin D status and susceptibility to respiratory and tuberculosis infections.

Why is LL-37 dose-dependent for cytotoxicity?

Like most amphipathic antimicrobial peptides, LL-37 is selectively toxic to bacterial membranes at low concentrations but loses selectivity at high concentrations, affecting host cell membranes as well. Research protocols need to balance antimicrobial efficacy against host cell tolerability, which is a general limitation of the class.

How should LL-37 be stored?

Keep the lyophilised powder frozen at −20 °C. After reconstitution with bacteriostatic water, refrigerate at 1-6 °C and protect from light. LL-37 is susceptible to proteolytic degradation, so use reconstituted material promptly and avoid repeated freeze-thaw cycles.

Lyophilised · batch-documented · discreet packaging

>99% Purity // Janoshik Verified // Human Cathelicidin // 37 Amino Acids

LL

Name: LL-37
Brand: New-U Research Peptides
SKU: ll-37
Availability: InStock

Human Cathelicidin Antimicrobial Peptide // CAMP // Innate Immune Defence

The human body's frontline antimicrobial peptide. Broad-spectrum defence against bacteria, viruses, fungi, and biofilms.

LL-37 is the only known member of the human cathelicidin family of antimicrobial peptides. Produced by neutrophils, epithelial cells, and macrophages as a first-line innate immune defence, LL-37 directly disrupts microbial membranes while simultaneously modulating TLR signalling, promoting wound healing, and exhibiting potent anti-biofilm activity. Research explores its role in chronic wounds, resistant infections, autoimmune conditions, and cancer immunotherapy.

37 Amino acids

Broad Spectrum activity

Human Endogenous peptide

Anti-Biofilm Disrupts resistant colonies

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Certificate of Analysis confirms peptide purity, amino acid composition, and absence of contaminants.

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Research-grade

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Research use only. All compounds are sold strictly for in-vitro research and educational purposes. Not approved for human use, therapeutic application, or as food or cosmetic products. By purchasing, you agree to use these products only for legitimate research purposes.

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