Immune Investigational

LL-37

Also known as: Cathelicidin, hCAP-18 (precursor), Human Antimicrobial Peptide

The only human cathelicidin — a broad-spectrum antimicrobial peptide that kills pathogens, modulates inflammation, and promotes wound healing as part of innate immune defense.

Popularity B
Class Cathelicidin Antimicrobial Peptide
Half-Life Short (minutes in serum — rapidly degraded by proteases)
Form Lyophilized powder
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LL-37 C205H340N60O53
Research-Backed User Reports Sourced Updated Mar 2026
// Overview

What is LL-37?

LL-37 is the sole member of the human cathelicidin antimicrobial peptide (AMP) family. It is a 37-amino acid peptide (beginning with two leucine residues, hence “LL”) that is produced by immune cells, epithelial cells, and other tissues as a first-line defense against pathogens.

LL-37 is far more than a simple antimicrobial. It functions as a multifaceted immune effector molecule that directly kills bacteria, viruses, and fungi; modulates inflammation; promotes wound healing and angiogenesis; and acts as a chemoattractant to recruit immune cells to infection sites.

Interest in LL-37 supplementation has grown due to research showing that deficiency or dysfunction of cathelicidin is associated with increased susceptibility to infections, chronic wounds, and certain skin conditions like rosacea. Exogenous LL-37 may help restore antimicrobial defense and immune function, particularly in individuals with compromised innate immunity.

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// How It Works

How LL-37 Works

LL-37 provides innate immune defense through multiple mechanisms:

  1. Direct antimicrobial killing — Forms pores in bacterial, viral, and fungal membranes through electrostatic interaction with negative-charged pathogen surfaces. Broad-spectrum activity against gram-positive, gram-negative bacteria, enveloped viruses, and fungi.
  2. Biofilm disruption — Penetrates and disrupts bacterial biofilms — the protective matrix that makes chronic infections resistant to antibiotics. This is a critical advantage over conventional antibiotics.
  3. Immune cell recruitment — Acts as a chemoattractant for neutrophils, monocytes, and T-cells, recruiting immune reinforcements to infection sites.
  4. Inflammation modulation — Modulates TLR signaling and cytokine production. Can both activate immune defense against pathogens and suppress excessive inflammation.
  5. Wound healing — Promotes angiogenesis and re-epithelialization, accelerating wound closure. Stimulates keratinocyte and fibroblast migration.
// Dosage Protocols

Dosage Information (User-Reported)

Disclaimer: Dosage information is compiled from user reports and published research. This is not medical advice. Consult a healthcare professional before use.
Level Dose Frequency Duration
Immune Support 50-100 mcg Daily (subcutaneous) 2-4 weeks
Anti-Infection 100-200 mcg Daily 2-4 weeks
Topical (Wound) Applied directly 1-2x daily Until healed

What to Expect

Day 1-3

Injection site may show mild immune reaction (redness, warmth). Systemic immune activation subtle.

Week 1-2

Users with chronic infections report improvement. Wound healing acceleration visible for topical use. General immune robustness improved.

Week 2-4

Full antimicrobial effects. Biofilm-related infections may begin resolving. Skin conditions improving. Immune defense noticeably stronger.

Note

Most beneficial for those with active infections, biofilm issues, or compromised innate immunity. Healthy individuals may notice less dramatic effects.

Common Stacks

Thymosin Alpha 1

Complete Immune Stack

LL-37 (innate antimicrobial) + Tα1 (adaptive T-cell immunity) = comprehensive immune defense covering both arms

BPC-157

Healing + Defense

LL-37 protects against infection while BPC-157 repairs tissue — ideal for wound management

Vitamin D3

Cathelicidin Induction

Vitamin D directly upregulates endogenous LL-37 production, amplifying the exogenous supplementation

// Preparation

Reconstitution & Storage

Reconstitute with bacteriostatic water. Handle carefully — LL-37 is sensitive to proteolytic degradation.

For subcutaneous use: Inject near areas of concern or systemically.

For topical use: Can be applied in solution to wounds or skin lesions.

Store reconstituted solution refrigerated and use promptly.

Storage: Lyophilized: -20°C. Reconstituted: 2-8°C, use within 7-14 days. Sensitive to degradation.

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// Safety Profile

Side Effects & Safety

Potential Side Effects

  • ! Injection site irritation and redness (immune activation)
  • ! Mild flu-like symptoms (immune response)
  • ! Skin irritation with topical use
  • ! Limited human supplementation safety data
  • ! Theoretical concern: excessive LL-37 is associated with inflammatory conditions (rosacea, psoriasis)

Contraindications

  • ⚠ Rosacea (LL-37 overexpression is implicated in rosacea pathogenesis)
  • ⚠ Active autoimmune skin conditions
  • ⚠ Pregnancy or breastfeeding
  • ⚠ Known hypersensitivity to cathelicidin peptides

Legal & Regulatory Status

Not FDA-approved. Research peptide. Available from select peptide vendors. Not a controlled substance. Active research area for antibiotic resistance and wound healing.

// Research

Published Research

// Where to Buy

Top Vendors for LL-37

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// Related Compounds

Other Immune Guides

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BPC-157 Arginate (Oral)

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TB-500 Fragment

A concentrated fragment of Thymosin Beta-4 focused on the core actin-binding domain — smaller molecule, targeted tissue repair.

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This content is for informational and educational purposes only. LL-37 is sold for research purposes. Never Natty does not condone or encourage the use of any substance in violation of any laws. Consult a healthcare professional before using any compound discussed on this site.