OnePin Peptide Library · Immune
LL-37
Cathelicidin · LL37 · hCAP-18
LL-37 is the only human cathelicidin antimicrobial peptide, a 37-amino acid peptide cleaved from the precursor protein hCAP18 by proteinase 3. It is a key component of the innate immune system, produced by neutrophils, macrophages, epithelial cells, and mast cells in response to infection. LL-37 directly kills bacteria, fungi, and enveloped viruses through membrane disruption, while also modulating immune cell recruitment, wound healing, and inflammatory signaling. It represents a naturally occurring antibiotic peptide that pathogens have difficulty developing resistance to due to its membrane-targeting mechanism.
Can be taken any time. Short courses (2-4 weeks) for infections. Pin alone or with limited safe compounds only.
Start here. Every protocol below is ordered lowest-first. Begin at the smallest effective dose, hold about a week to assess tolerance, and step up only if needed.
How it works
LL-37 adopts an amphipathic alpha-helical structure that inserts into microbial membranes, creating pores that disrupt membrane integrity and kill pathogens. This mechanism is effective against gram-positive and gram-negative bacteria, fungi, and enveloped viruses. Beyond direct killing, LL-37 recruits immune cells to infection sites (chemotaxis), modulates inflammatory cytokine production, neutralizes bacterial endotoxin (LPS), promotes angiogenesis and wound healing, and disrupts bacterial biofilms that protect chronic infections.
LL-37 adopts an amphipathic alpha-helical structure that inserts into microbial membranes, creating pores that disrupt membrane integrity and kill pathogens. This mechanism is effective against gram-positive and gram-negative bacteria, fungi, and enveloped viruses. Beyond direct killing, LL-37 recruits immune cells to infection sites (chemotaxis), modulates inflammatory cytokine production, neutralizes bacterial endotoxin (LPS), promotes angiogenesis and wound healing, and disrupts bacterial biofilms that protect chronic infections.
What to expect
Days 1-7: Immune augmentation begins. Most relevant during active infection.
Weeks 2-4: Chronic infection support. Biofilm disruption effects accumulate.
Short courses typical. Extended use not standard.
Evidence
The honest take
Natural antibiotic
Confirmed. LL-37 directly kills pathogens through membrane disruption. Resistance development is difficult because mechanism targets fundamental membrane structure.
Confirmed in vitro and animal models. Relevant for chronic infections with biofilm component.
Interactions & stacking
What's safe to combine, and what belongs in a separate pin.
Safe & synergistic
Keep separate
Side effects & safety
Commonly reported
- Injection site irritation
- Mild redness
Less common & notes
- LL-37 is endogenously produced.
- At high concentrations, antimicrobial peptides can theoretically be cytotoxic to host cells.
- Stick to standard dosing ranges.
Pharmacokinetics
Storage. Standard BAC water 2-8C. Stable for 28 days. Protect from light.
Regulatory status
Not FDA-approved as injectable. Available as research peptide. WADA status not specifically listed.
Put it to work
Calculate, log & track
Open LL-37 straight into OnePin with your vial and dose pre-filled, then let it handle the syringe math and remind you before the vial runs out.
Open LL-37 in the app →Go deeper
The guide & community
The complete LL-37 walkthrough, real protocol discussion and coaching live inside the BlessUp community on Skool.
Join the community ↗