LL-37

LL-37 is a human cathelicidin antimicrobial peptide produced by neutrophils and epithelial cells. It has broad antimicrobial activity and also modulates innate immunity, inflammation, and wound healing. In research it is explored for anti-biofilm effects and immune modulation, but dosing and safety require caution due to potential inflammatory effects.

— 5 mg Vial —

Reconstitute: Add 3.0 mL bacteriostatic water → ~1.67 mg/mL concentration.
Typical daily range: 100–400 mcg once daily (gradual titration).
Easy measuring: At 1.67 mg/mL, 1 unit = 0.01 mL ≈ 16.7 mcg on a U-100 insulin syringe.
Storage: Lyophilized: freeze at −20 °C; reconstituted: refrigerate at 2–8 °C for up to 4 weeks, avoid freeze-thaw cycles.

Schedule: Daily subcutaneous injections for 8–12 weeks (extend to 16 weeks if desired).
Cycle Length: 8–12 weeks; optional extension to 16 weeks.
Goal: Support antimicrobial defense and wound-healing processes.

Frequency: Inject once daily subcutaneously. Some protocols use a 5-days-on, 2-days-off schedule.

• Broad-spectrum antimicrobial activity in vitro
• Anti-biofilm activity against certain pathogens (preclinical)
• Immunomodulatory effects on chemotaxis and cytokine signaling
• May influence wound healing and angiogenesis pathways
• Tool peptide for innate immunity research

• Cationic amphipathic peptide disrupts microbial membranes
• Can bind LPS and modulate endotoxin responses
• Signals via receptors including FPR2 and P2X7 affecting chemotaxis/inflammation
• Context-dependent activation of inflammatory pathways

• Injection-site irritation
• Flu-like symptoms
• Increased inflammation or pain (context-dependent)
• Headache
• Fever/chills
• Potential worsening of autoimmune/inflammatory conditions (theoretical)

• Use conservative dosing and short cycles; monitor inflammatory symptoms
• Avoid use during active inflammatory flares in susceptible subjects
• Sterile technique and careful handling are essential
• Discontinue if systemic inflammatory symptoms occur

• Autoimmune diseases or chronic inflammatory disorders (caution/avoid)
• Pregnancy/nursing
• Hypersensitivity
• Do not substitute for standard infection treatment

1. Cathelicidin LL-37: multifunctional roles in host defense. Nat Rev Immunol. PubMed | DOI
2. The human cathelicidin antimicrobial peptide LL-37 and its derivatives. J Leukoc Biol. PubMed | DOI
3. LL-37 and autoimmune disease. Autoimmun Rev. PubMed | DOI
4. Antimicrobial peptide LL-37 in wound healing. J Invest Dermatol. PubMed | DOI