Beginner view — everything explained simply.
Machine-assisted translation — the German original version is authoritative.
Longevity & Immune system
LL-37 (Cathelicidin)
Cathelicidin LL-37 · hCAP18/LL-37 · CAMP · FALL-39 · humanes Cathelicidin
LL-37 is the only known human cathelicidin — an endogenous antimicrobial peptide of 37 amino acids that arises from cleavage of the precursor protein hCAP18. It is produced by neutrophils and epithelial cells (skin, airways, gut) and is a building block of the innate immune defense: it acts against bacteria, viruses and fungi while also modulating inflammation and wound healing. In research it is regarded as „pleiotropic“, meaning it acts in many ways. As an administered substance, LL-37 is experimental and not approved as a medicine; robust, independently replicated human data on its use are limited. Much of what is known about LL-37 comes from laboratory, cell and animal models.
Regulatory status
Not approved for humans
Not approved as a medicine — an endogenous peptide that, as an administered substance, is experimental/a subject of research.
Drug class
Endogenous antimicrobial peptide (cathelicidin, 37 amino acids)
Half-life (informative)
Short; as a cationic peptide it is sensitive to proteases and degradation. Robust human pharmacokinetic data on the administered substance are limited.
Studied in the literature
Studied in various ways in the literature: among others topically (wound models), injected intratumorally (early oncological study), and orally in a small exploratory study. This only describes HOW the research proceeded — it is not a usage instruction.
Mechanism of action
LL-37 is a cationic, amphipathic peptide with an α-helical structure. Its positive charge lets it bind to negatively charged components of microbial membranes, which it can destabilize and make permeable — from which its direct antimicrobial effect arises. Beyond that, it binds and neutralizes bacterial lipopolysaccharide (LPS), thereby acting to modulate inflammation. Through interactions with host cells (including chemotaxis of immune cells, promotion of angiogenesis and epithelial/fibroblast activity) it is associated with wound healing and tissue regeneration. It shows both pro- and anti-inflammatory effects depending on context — a complexity that forbids classifying it as a pure „healing peptide“.
The activity of LL-37 is strongly context- and concentration-dependent; in vitro it can, at higher concentrations, also damage the body's own cells. Findings from laboratory and animal models cannot be transferred directly to humans.
Research history
LL-37 was described in the mid-1990s as the human cathelicidin (an early designation was FALL-39, after its first amino acids). The precursor protein was named hCAP18 (human cationic antimicrobial protein, 18 kDa); the active fragment LL-37 arises through extracellular cleavage, including by the enzyme proteinase-3. The associated gene (CAMP) lies on chromosome 3. Since then LL-37 has been studied intensively in the context of innate immunity, skin biology, airway and gut diseases, and — controversially — tumor biology.
Regulatory status by region
Not an approved medicine; LL-37 is a subject of research, not an established approved use.
No regular marketing authorization; individual clinical trials (including a completed phase 1/2 melanoma study) were conducted without leading to an approval.
As an endogenous peptide it is biologically well characterized, but as a therapeutically administered substance it has no established approval.
Research areas
- Innate immune defense and antimicrobial/anti-biofilm activity (predominantly preclinical)
- Wound healing and tissue regeneration (laboratory/animal models, early topical approaches)
- Inflammation modulation and LPS neutralization
- Tumor biology — with contradictory findings (both tumor-promoting and tumor-inhibiting effects depending on tumor type)
- Skin, airway and gut diseases (including rosacea, psoriasis, inflammatory bowel diseases)
Documented effects (from the literature)
- Documented in preclinical models: broad antimicrobial and anti-biofilm activity against gram-positive and gram-negative pathogens.
- Described promotion of chemotaxis, angiogenesis and wound-healing processes in cell and animal models.
- Both pro- and anti-inflammatory effects depending on concentration and tissue context.
Safety concerns & caution
- Robust, independently replicated human evidence on the administered substance is limited; much rests on laboratory and animal data.
- At higher concentrations LL-37 can act cytotoxically on the body's own cells in vitro — the therapeutic window is delicate.
- In tumor research there are contradictory findings: LL-37 has been associated with the promotion of some tumor types (e.g. local invasion in melanoma) and with the inhibition of others. This ambivalence is not conclusively resolved.
- An involvement in inflammatory skin diseases (e.g. rosacea, psoriasis) and autoimmune processes is being discussed.
- The long-term safety of an administered use in humans is not established.
Risks of gray-market purchase
- It is marketed as a „research peptide“ for „immune strengthening“ or „wound healing“ — these self-administration promises are not backed by approvals or robust human studies.
- The purity, sterility and actual peptide content of gray-market vials are unverified; contaminants are possible.
- The ambivalent role in tumor biology makes uncontrolled self-administration particularly hard to assess.
- Community claims of rapid wound healing or an „immune boost“ are to be understood as claims, not as a proven fact.
Frequently asked questions
Is LL-37 a „natural“ and therefore harmless peptide?
LL-37 is indeed endogenous and part of the innate immune defense. But „endogenous“ does not automatically mean „harmless as a medication“: at higher concentrations it can also damage the body's own cells, and its role in inflammation and tumor biology is ambivalent. An administered use is not approved and not well backed by human studies.
Is there evidence that administered LL-37 heals wounds or strengthens the immune system?
Most of the evidence comes from laboratory, cell and animal models as well as small, early studies. Robust, independently replicated human evidence for a therapeutic use is largely lacking. Statements about „wound healing“ or an „immune boost“ are therefore to be read as research hypotheses, not as an established effect.
Why does LL-37 appear in both cancer inhibition and cancer promotion?
That is precisely one of the biggest open questions. Depending on the tumor type and context, LL-37 has been described with promoting (e.g. local invasion in melanoma) and with inhibiting effects. These contradictions are not resolved and are an important reason why an uncontrolled use is problematic.
Sources
Primary and reference sources for your own reading.
- PubMedLL-37, the only human member of the cathelicidin family of antimicrobial peptides (Dürr et al., 2006)
- PubMedLL-37: Cathelicidin-related antimicrobial peptide with pleiotropic activity (Fabisiak et al., Pharmacol Rep 2016)
- PubMed CentralThe Human Cathelicidin Antimicrobial Peptide LL-37 as a Potential Treatment for Polymicrobial Infected Wounds (Duplantier & van Hoek, Front Immunol 2013)
- ClinicalTrials.govInduction of Antitumor Response in Melanoma Patients Using the Antimicrobial Peptide LL37 (abgeschlossene Phase-1/2-Studie)
Related substances
Unfamiliar terms? Look them up in the glossary or read the fundamentals.
This profile is for information and education only. It is not medical advice and deliberately contains no dosing or usage details. Decisions about use belong in a doctor’s hands.