LL-37
Also known as: Cathelicidin LL-37, hCAP-18 C-terminal fragment, CAMP peptide
Overview
LL-37 is a 37-amino acid cationic antimicrobial peptide (AMP), the only known member of the cathelicidin family in humans. It is generated by proteolytic cleavage of the precursor protein hCAP-18 by serine proteases. LL-37 adopts a characteristic amphipathic alpha-helical structure in membrane environments that is critical for its membrane-disrupting antimicrobial activity. Beyond killing microbes, LL-37 has extensive immunomodulatory, wound-healing, and anti-cancer properties, making it a multifunctional innate immune molecule.
Mechanism of Action
LL-37's antimicrobial mechanism involves electrostatic interactions with negatively charged bacterial membranes (via its cationic charge), insertion into the lipid bilayer (facilitated by amphipathic helix), and pore formation and membrane disruption leading to bacterial cell death. It binds bacterial LPS (lipopolysaccharide), neutralizing endotoxin activity. Immunomodulatory effects include: chemotaxis of immune cells to infection sites; cytokine release modulation; enhancement of wound healing via promotion of cell migration and re-epithelialization; and angiogenesis promotion. It also demonstrates activity against enveloped viruses (influenza, HSV, RSV, HIV-1) through viral envelope disruption.
Potential Benefits
- Broad-spectrum antimicrobial activity against Gram-positive and Gram-negative bacteria including MRSA
- Antifungal activity against Candida albicans
- Antiviral activity against enveloped viruses
- Wound healing acceleration via re-epithelialization and angiogenesis
- Immunomodulation guiding immune cells to infection sites
- LPS neutralization reducing septic shock potential
- Synergistic antimicrobial activity with beta-defensin-2 and lysozyme
Dosage Protocols
The following reflects doses used in published research studies. This is not medical advice. Consult a qualified healthcare professional.
| Typical Range | 10-50 mcg/day topical; 100-200 mcg/day injectable (research) |
| Beginner | 25 mcg/day topically or 100 mcg/day subcutaneously |
| Intermediate | 50 mcg/day topically or 150 mcg/day subcutaneously |
| Advanced | 100-200 mcg/day subcutaneously; higher topical concentrations |
| Cycle Duration | 4-8 weeks |
| Cycle Off | 4 weeks |
Primarily studied as a topical antimicrobial and wound healing agent. Injectable LL-37 is experimental. High systemic doses could cause off-target membrane disruption effects; use caution with injectable forms.
Use our Reconstitution Calculator to determine exact syringe units for your protocol.
Routes of Administration
Subcutaneous Injection Moderate — local and systemic immune effects
Standard method for immune modulation. Typical dose 50–100 mcg daily.
Topical Application Local skin/wound effects
Applied directly to wounds or skin infections. LL-37 promotes wound healing and has direct antimicrobial activity at the application site.
Intranasal Moderate — direct respiratory tract delivery
Used for upper respiratory infections and sinus conditions. Direct antimicrobial action on nasal/sinus mucosa.
Read our full Routes of Administration Guide for detailed comparison of all delivery methods.
Stacking Protocols
Popular research stacks involving LL-37:
Immune Defense Stack
Comprehensive immune support. LL-37 provides direct antimicrobial action while Thymosin Alpha-1 activates adaptive immunity via dendritic cell maturation and T cell enhancement.
Wound & Infection Stack
Antimicrobial healing. LL-37 kills pathogens at wound site, BPC-157 promotes tissue repair, GHK-Cu stimulates collagen and skin regeneration.
Explore our complete Peptide Stacking Guide for more combinations and safety considerations.
Reconstitution
| Typical Vial Size | 2mg, 5mg |
|---|---|
| BAC Water | 1-2ml per 2mg vial |
| Storage | Refrigerate at 2-8°C after reconstitution; topical formulations at room temperature |
| Shelf Life | 14-28 days refrigerated (injectable) |
Need exact syringe measurements?
Amino Acid Sequence
LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES (37 amino acids)
Side Effects & Safety
- Cytotoxicity to mammalian cells at high concentrations
- Pro-inflammatory effects at certain concentrations (paradoxical)
- Potential to promote bacterial resistance via virulence upregulation
- Hemolytic activity at high doses
Safety & Contraindications
This information is for educational purposes only. Consult a qualified healthcare provider before using any peptide.
Pregnancy / Lactation
Bleeding Disorders
Active Skin Infection at Injection Site
FDA Safety Information
FDA Category 2 concerns: immunogenicity, detrimental effects on male reproduction, protumorigenic potential.
Pharmacokinetics
| Half-Life | Short (minutes) in serum due to proteolysis; longer tissue residence |
|---|---|
| Storage | Store lyophilized peptide at -20°C (long-term) or 2-8°C (short-term, under 30 days). Reconstituted: refrigerate at 2-8°C and use within 28-30 days. Protect from light. Do not freeze reconstituted solution. |
Synergistic Compounds
The following compounds have been studied alongside LL-37 for potential complementary or synergistic effects:
Learn More
References & Further Reading
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