Common Dosage
100mcg - 500mcg daily (injectable or topical)
Category
Immunity
- Antimicrobial activity
- Wound healing
- Immune modulation
- Biofilm disruption
LL-37 is the only cathelicidin antimicrobial peptide produced by humans, encoded by the CAMP gene on chromosome 3. It was first characterized in the early 1990s. LL-37 is generated when the cathelicidin precursor protein (hCAP-18) is cleaved by proteinase 3 in neutrophil granules or by kallikrein in epithelial cells. It plays a critical role in the first line of innate immune defense against bacteria, viruses, and fungi — and is synthesized in increased quantities by skin, lung, gut, and immune cells during infection or injury.
LL-37 exerts antimicrobial activity through multiple mechanisms: it disrupts bacterial membranes through electrostatic interaction with lipopolysaccharide (gram-negative) or lipoteichoic acid (gram-positive), it neutralizes bacterial toxins and endotoxins, and it inhibits biofilm formation. Beyond antimicrobial activity, it is a potent immune modulator — stimulating chemokine production to recruit immune cells, activating EGFR to promote wound healing, and acting as a direct neutrophil and macrophage activator. It also has antiviral activity against influenza, HIV, and other viruses.
- Infection management — bacterial, fungal, and viral
- Biofilm disruption for antibiotic-resistant infections
- Wound healing acceleration
- Chronic inflammatory skin conditions (psoriasis, rosacea)
- Respiratory infection support (bronchial epithelial antimicrobial defense)
- Cancer — both pro- and anti-cancer roles depending on context
Antibiotic-Resistant Infection Support
Clinical case reports of LL-37 use in antibiotic-resistant infections (particularly MRSA and Pseudomonas biofilm infections) have documented reduced bacterial burden and improved wound healing when LL-37 is applied topically or used systemically alongside antibiotics.
Wound Healing
LL-37 has demonstrated accelerated wound closure in diabetic wound models through EGFR activation and enhanced keratinocyte migration — providing a mechanistic basis for its clinical use in chronic wounds.
- Injection site irritation and inflammatory response are consistent, particularly at higher doses
- LL-37 has a complex and context-dependent relationship with cancer — it is both reported to suppress some tumors while enhancing others. Active cancer is a contraindication
- Immune over-activation in autoimmune conditions — cathelicidins have been implicated in the pathogenesis of some autoimmune skin and inflammatory conditions
- Stability is limited after reconstitution
- Significant variability in bioavailability via different routes
- Injection site irritation
- Inflammatory response at high doses