LL-37
Antimicrobial Peptide / Immune ModulatorAlso known as: Cathelicidin · hCAP-18 C-terminal fragment
The only human cathelicidin antimicrobial peptide. Kills pathogens directly, modulates inflammation, promotes wound healing, & has angiogenic & anti-tumor properties.
Typical Dose
50–300 mcg 2–3x per week
Route
Subcutaneous injection
Cycle
2–6 weeks
Half-life
Short (minutes in plasma; protease-sensitive)
Storage
Lyophilized: 2–8°C. Reconstituted: 2–8°C, use within 14 days.
Overview
LL-37 is a 37-amino-acid cationic peptide derived from the C-terminal domain of the human cathelicidin precursor hCAP-18. It is the only cathelicidin found in humans & is produced by neutrophils, epithelial cells, macrophages, & mast cells at sites of infection & inflammation.
Its mechanism involves direct membrane disruption of bacteria, fungi, & enveloped viruses through its amphipathic alpha-helical structure. Beyond direct antimicrobial killing, LL-37 modulates TLR signaling, promotes angiogenesis via VEGF upregulation, accelerates wound healing, & has demonstrated anti-tumor activity in animal models.
Clinical development has focused on topical & inhaled formulations for chronic wound infection & lung disease. Systemic injection-based use is primarily a research context given its complex immunomodulatory profile.
Quick Start Guide
Start with 50–100 mcg SubQ 2–3x per week. Dose escalation is not well characterized; stay conservative.
Intended for short cycles (2–4 weeks) during or after active infection or wound healing.
Research Indications
Antimicrobial (broad spectrum)
Most EffectiveKills Gram-positive, Gram-negative bacteria, fungi, & enveloped viruses via membrane disruption. Effective against drug-resistant strains (MRSA, etc.) in vitro.
Wound healing & angiogenesis
EffectivePromotes keratinocyte migration, angiogenesis, & re-epithelialization. Studied for chronic wound treatment.
Anti-tumor activity
Research OnlyInduces apoptosis in some tumor cell lines. Animal studies show tumor growth inhibition. No human data.
Research Protocols
Infection support / immune modulation
2–4 weeksDose
100–200 mcg
Frequency
2–3x weekly
Route
SubQ abdomen
Peptide Interactions
No known interaction. May complement wound healing through different mechanisms.
Side Effects & Safety
Common
- Injection site redness & burning (cationic amphipathic peptide — local irritation is common)
- Flushing
Uncommon
- Systemic inflammatory response at high doses
- Headache
When to Stop
- Signs of systemic inflammatory reaction
- Hypersensitivity
- Active autoimmune disease (LL-37 is elevated in lupus & psoriasis; adding exogenous LL-37 is theoretically contraindicated)
How to Reconstitute
Reconstitute with 1–2 mL bacteriostatic water.
Swirl gently. May require longer dissolution time than smaller peptides.
Refrigerate. Use within 14 days.
Dosing math: Concentration varies by vial size. Typical: 1 mL BAC water per 1 mg = 1000 mcg/mL.
Quality Indicators
Good — use as normal
- Clear solution — LL-37 is a larger peptide & should dissolve fully
Acceptable
- Slight opalescence clearing within 5 minutes
Discard immediately
- Gel-like consistency
- Persistent particulate
- Strong discoloration
What to Expect
Week 1
Antimicrobial activity begins immediately. Local injection site reactions are most pronounced in week 1.
Week 2–4
Wound healing acceleration (if applicable). Immune modulation effects accumulating.
Community Insights
Self-reported. Reflects user experience, not clinical outcomes.
Research References
LL-37, the only human member of the cathelicidin family of antimicrobial peptides
Biochimica et Biophysica Acta · 2006
Comprehensive review of LL-37 structure, antimicrobial mechanisms, immunomodulatory functions, & therapeutic potential.
Verify what you have
Information on this page applies to pharmaceutical-grade peptides. Purity & identity of research-grade products vary. Certipep provides independent ESI-TOF-MS & HPLC analysis with a signed analytical report.
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