⚠️ Research Use Only. This post is educational and does not constitute medical advice. All peptides discussed are sold for research purposes only. See our full disclaimer.
Overview
LL-37 is a human antimicrobial peptide studied for its broad-spectrum antimicrobial, anti-biofilm, and immune-modulating properties.
What is LL-37?
LL-37 is the only human cathelicidin antimicrobial peptide — a 37-amino-acid peptide produced by neutrophils, epithelial cells, and other immune cells. It's part of the innate immune system's frontline defense and has attracted research attention because it can kill bacteria that have evolved resistance to conventional antibiotics.
Mechanistically, LL-37 works very differently from traditional antibiotics. It physically disrupts bacterial membranes through electrostatic and hydrophobic interactions, which means resistance is harder for bacteria to develop. It also has potent anti-biofilm activity — the slimy bacterial communities that conventional antibiotics struggle to penetrate.
Beyond direct antimicrobial action, LL-37 modulates immune signaling. It enhances chemotaxis of neutrophils and monocytes, influences cytokine production, and plays roles in wound healing. Some research has examined LL-37 in chronic Lyme, biofilm-driven infections, and chronic sinusitis.
LL-37 has a more complicated side effect profile than most peptides. High doses can trigger histamine release, causing flushing and hypotension. Some patient communities use LL-37 in chronic inflammatory response syndromes — a use case that is well outside mainstream medicine and lacks controlled trial data. Dosing in published research varies widely; 100-500 mcg subcutaneous is a common research range.
Top Research Uses
- Antimicrobial research
- Biofilm disruption
- Wound healing
- Immune modulation
- Chronic infection research
Mechanism of Action
Disrupts bacterial membranes through electrostatic interactions, modulates innate immune signaling, and influences cytokine production
Research Parameters
| Half-Life | Short, ~30 minutes; activity duration varies by formulation |
| Typical Research Dose | Research protocols vary widely; commonly 100-500 mcg subq |
| Administration Route | Subcutaneous, intranasal, topical |
| Reported Side Effects | Histamine release possible; flushing, injection site reactions; high doses can cause hypotension |
Dosing ranges cited from published research literature. These are not recommendations for human use. LL-37 is a research compound — not for human consumption.
Research Strength: Moderate
LL-37 has a moderate research base, with a reasonable number of studies examining its proposed mechanisms. More research is ongoing.
Vendor & Sourcing Notes
Sold as research-grade peptide; some chronic infection research communities use it
Always request third-party HPLC purity reports and mass spectrometry verification when sourcing research peptides. Quality varies significantly between suppliers.
Research Use Only — Compliance Notice
The information on this page is intended for educational and informational purposes only. LL-37 (Cathelicidin LL-37) is a research compound sold for laboratory research purposes only. It has not been approved by the FDA for human use. Nothing on this page constitutes medical advice or is intended to diagnose, treat, cure, or prevent any disease. Statements have not been evaluated by the FDA. Consult a qualified healthcare professional before considering any peptide-related protocols.
