# LL-37

> Evidence tier A — Controlled human trials · Longevity & Immune · reviewed 2026-11-08
> Source page: https://peptidemeta.com/p/ll-37/

Also known as: Cathelicidin LL-37, CAMP (cathelicidin antimicrobial peptide)

## Quick answers

**What is LL-37?**

The only human cathelicidin antimicrobial peptide, LL-37 plays a key role in innate immunity by disrupting microbial membranes and modulating inflammatory signaling.

**How strong is the evidence for LL-37?**

Tier A (controlled human trials) on the peptidemeta evidence scale. Randomized placebo-controlled trials of topical LL-37 for venous leg ulcers (2014 phase 1/2; 2021 multicentre phase 2b) and diabetic foot ulcers (2023). Not approved anywhere.

**Is LL-37 FDA-approved?**

No. LL-37 is not approved by the FDA for any use.

**Is LL-37 banned in sport?**

Yes. LL-37 is prohibited in sport by the World Anti-Doping Agency under S0 (non-approved substances).

**How does LL-37 work?**

LL-37 is a 37-amino-acid amphipathic alpha-helical peptide that disrupts microbial membranes through electrostatic interaction with negatively charged lipid bilayers. Beyond direct antimicrobial killing, it acts as an immune alarmin by binding formyl peptide receptor 2 (FPR2) to recruit neutrophils, monocytes, and T-cells, and it disrupts bacterial biofilms.

**What is known about the safety of LL-37?**

Endogenous human peptide with well-established innate immune biology. Injection of exogenous LL-37 carries risk of excessive inflammation at high doses.

## Key facts

- **Evidence tier:** A (Controlled human trials)
- **FDA:** not approved
- **WADA:** prohibited (S0)
- **Peptide:** yes
- **Sequence:** LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES (37 residues)
- **Formula:** C205H340N60O53
- **Molecular weight:** 4493 g/mol
- **Routes studied:** Subcutaneous, Intramuscular

## Overview

The only human cathelicidin antimicrobial peptide, LL-37 plays a key role in innate immunity by disrupting microbial membranes and modulating inflammatory signaling.

## Mechanism

LL-37 is a 37-amino-acid amphipathic alpha-helical peptide that disrupts microbial membranes through electrostatic interaction with negatively charged lipid bilayers. Beyond direct antimicrobial killing, it acts as an immune alarmin by binding formyl peptide receptor 2 (FPR2) to recruit neutrophils, monocytes, and T-cells, and it disrupts bacterial biofilms.

## Effects reported in research

_Reported outcomes, not promises; see the evidence tier._

- Broad-spectrum antimicrobial activity
- Biofilm disruption on mucosal surfaces
- Immune cell chemotaxis and activation
- Wound healing acceleration

## Safety & unknowns

Endogenous human peptide with well-established innate immune biology. Injection of exogenous LL-37 carries risk of excessive inflammation at high doses. Potential for mast cell activation. Limited formal clinical trial data for therapeutic injection. Not FDA-approved.

## Studies

- Vandamme D, Landuyt B, Luyten W, et al. (2012). *A comprehensive summary of LL-37, the factotum human cathelicidin peptide*. Cellular Immunology. Review. https://pubmed.ncbi.nlm.nih.gov/23246832/
  Review of LL-37 covering its antibacterial, antifungal and antiviral activity, chemotactic and immunomodulatory effects, and roles in wound healing.
- Grönberg A, Mahlapuu M, Ståhle M, et al. (2014). *Treatment with LL-37 is safe and effective in enhancing healing of hard-to-heal venous leg ulcers: a randomized, placebo-controlled clinical trial*. Wound Repair and Regeneration. Clinical trial. https://pubmed.ncbi.nlm.nih.gov/25041740/
  Randomized placebo-controlled trial of topical LL-37 in patients with hard-to-heal venous leg ulcers, assessing safety and ulcer healing.

## Status sources

- [Grönberg et al. 2014 — LL-37 for venous leg ulcers, RCT](https://pubmed.ncbi.nlm.nih.gov/25041740/)
- [Mahlapuu et al. 2021 — multicentre RCT of LL-37 in venous leg ulcers](https://pubmed.ncbi.nlm.nih.gov/34687253/)
- [UniProt P49913 — cathelicidin antimicrobial peptide](https://www.uniprot.org/uniprotkb/P49913/entry)
- [PubChem CID 16198951 (LL-37)](https://pubchem.ncbi.nlm.nih.gov/compound/16198951)
- [WADA 2026 Prohibited List — S0 non-approved substances](https://www.wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf)

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Educational reference only — not medical advice. No dosing information is published. Tiers rate the strength of published evidence, not effectiveness or safety.