⚠ Educational reference only — not medical advice.** This article is for research and educational reference. Always consult your own physician before considering any peptide protocol. See the full Disclaimer at the end of this article.

Introduction
LL-37 is the sole mature human cathelicidin — a 37-amino-acid amphipathic α-helical cationic peptide cleaved from the inactive precursor hCAP-18 by proteinase 3 in neutrophils and other cells. Central effector of innate immunity at epithelial surfaces. Investigational as a finished therapeutic; not FDA-approved.

Mechanism of Action
Disrupts bacterial membranes via electrostatic interaction with anionic lipids (the “carpet” mechanism), retaining activity against many antibiotic-resistant Gram-negative and Gram-positive organisms. Beyond direct microbicidal activity, LL-37 modulates the host immune response — neutrophil/monocyte chemotaxis, dampening of LPS-driven inflammation, and angiogenic signaling that supports wound healing.

Research Indications
Chronic wounds (venous ulcers, diabetic foot ulcers), antibiotic-resistant skin and soft-tissue infections, biofilm-associated infections, and rosacea (where LL-37 dysregulation is implicated). Immune-modulation research in autoimmune disease.

Reconstitution
Typical 5 mg lyophilized vial: add **2.5 mL of bacteriostatic water**, swirl gently. Final concentration **2000 mcg/mL (2 mg/mL)** — each 0.05 mL (5 units on a U-100 insulin syringe) delivers 100 mcg.

Dosing Protocol (research literature)
Research protocols typically dose **100–500 mcg subcutaneously once daily** for systemic protocols; **higher topical concentrations** (varied vehicle) for wound applications. Cycle length **2–4 weeks** with reassessment; longer durations are not well-characterized for the systemic SC route.

Administration
Subcutaneous into abdominal fat for systemic protocols. Topical application directly to the wound bed in wound-care protocols (typically with a saline or aqueous vehicle).

Storage & Handling
Lyophilized: refrigerate (2–8°C); freeze (–20°C) for long-term storage. Reconstituted: refrigerate; stable approximately **7–14 days** — LL-37 is protease-sensitive and concentration declines noticeably in solution. Protect from light.

Side Effects
Local injection-site reactions most common. Systemic high-dose exposure can produce cytotoxicity and pro-inflammatory effects — dose and concentration matter substantially. LL-37 is implicated as an autoantigen in psoriasis pathophysiology.

Contraindications
Pregnancy, lactation, active autoimmune skin disease (especially psoriasis), and hypersensitivity to cathelicidin-class peptides.

Monitoring
Baseline wound-area measurement (digital photography or planimetry), CBC, CRP for systemic protocols. Re-measure wound endpoints weekly; systemic biomarkers at 4 and 8 weeks.

Disclaimer
**This article is for informational and research-reference purposes only.** Nothing in this document constitutes medical advice, a prescription, or a recommendation from a physician. The reconstitution, dosing, and protocol information above reflects ranges commonly cited in published research and clinician-directed protocols — it is provided as reference material only, not as instructions, an endorsement of off-label use, or a substitute for individualized medical evaluation.

**Customers should do their own research and consult their own physician** before considering any peptide protocol. Whether a given compound is appropriate for an individual — and at what dose, for what duration, and alongside what monitoring — is a decision that only a licensed clinician with knowledge of that individual’s medical history, current medications, and conditions can make.