LL-37 (Cathelicidin)
LL-37 (Cathelicidin) scored 4.6 / 10 (⚖️ Neutral) on the BioHarmony scale as a Substance → Peptide → Immune Peptide.
LL-37 (Cathelicidin) is the only human cathelicidin antimicrobial peptide, with a rich antimicrobial and wound-healing mechanism but thin human therapy data: one small topical leg-ulcer trial of 34 people per Gronberg 2014, and a documented double-edge as a psoriasis autoantigen and cancer growth factor.
What is LL-37 (Cathelicidin)?
LL-37 (Cathelicidin) is the only antimicrobial peptide the human body makes from the cathelicidin family, and that single fact explains both its appeal and its caution rating. It is a short, charged 37-residue helix cut from a precursor protein and switched on by vitamin D, infection, inflammation, and wounding. In one molecule it kills microbes, breaks up biofilms, mops up bacterial toxins, calls in immune cells, and helps wounds close. That breadth is real and genuinely impressive, and it is backed by a large mechanistic literature spanning antimicrobial, immune, and wound-repair biology. The reason this report still lands in caution is the gap between that rich mechanism and actual human proof, plus a documented double-edge that the grey market does not advertise. The strongest human study to date is a single small topical wound trial, which tells you how thin the therapeutic record really is once you move past the test tube.
Here is the honest split. The only solid human therapy evidence is a single small topical trial in leg ulcers, and there is zero human efficacy data for the injectable systemic use sold online. At the same time, LL-37 is a confirmed trigger of autoimmune disease and a growth factor for several cancers. So you have a peptide with a beautiful mechanism, one promising topical result, and two well-documented ways it can hurt you. That combination is exactly what a caution score is for. The peptide is native to your body, but injecting extra is a different story than the tightly regulated amounts your cells release on their own.
Terminology
A few terms decide how you read this report, because LL-37 is one molecule wearing many hats, and the same property that protects you can harm you in the wrong setting. Getting these straight is what separates the hype from the honest picture.
- Cathelicidin: The family of host-defense peptides. Humans make exactly one, and its active fragment is LL-37.
- hCAP-18: The precursor protein. LL-37 is the piece cut off the end of it by an enzyme.
- CAMP gene: The gene that codes for the precursor. It is switched on by the vitamin-D receptor.
- Antimicrobial peptide: A small protein that kills microbes directly, usually by breaking their membranes.
- Biofilm: A protective slime layer bacteria build to resist antibiotics. LL-37 can break these up in the lab.
- Autoantigen: A self-molecule the immune system wrongly attacks. LL-37 is a confirmed one in psoriasis.
- Alarmin: A molecule that raises the immune alarm. This is why LL-37 can be pro-inflammatory, not just calming.
- LPS: Lipopolysaccharide, a bacterial toxin. LL-37 binds and neutralizes it.
- FPR2: The receptor LL-37 uses for much of its immune and tumor signaling.
- Inverted-U dose response: A pattern where a middle or low dose works best and a higher dose works worse, seen in the one human trial.
How do you take LL-37 (Cathelicidin)?
Dosing & Protocols
Dosing information is summarized from published research and community reports. This is not a prescribing guide. Consult a healthcare provider before starting any protocol.
View 2 routes and 4 protocols
Routes & Forms
| Route | Form | Clinical Range | Community Range |
|---|---|---|---|
| Topical (the only evidence-based route) | Aqueous solution applied to the wound bed | Twice-weekly application; the leg-ulcer trial found 0.5 mg/mL most effective and 3.2 mg/mL no better than placebo | Not standardized outside the trial |
| Subcutaneous injection (grey-market, not evidence-based) | Lyophilized powder reconstituted with bacteriostatic water | No approved clinical dose for any systemic use | Commonly cited 100 to 400 mcg once daily, titrated up from 50 to 100 mcg |
Protocols
Topical wound care (closest to evidence) Mixed
- Dose
- 0.5 mg/mL solution to the wound bed
- Frequency
- Twice weekly
- Duration
- About 4 weeks in the trial
This mirrors the only positive human trial. The lowest concentration outperformed the highest, so escalating the dose is the wrong move.
Conservative injectable starter (grey-market, anecdotal) Anecdotal
- Dose
- 50 to 100 mcg
- Frequency
- Once daily
- Duration
- 8 weeks, then reassess
No human evidence supports this. Listed only to show what vendors promote, with the warning that systemic dosing has no safety basis.
Standard injectable (grey-market, anecdotal) Anecdotal
- Dose
- 100 to 200 mcg
- Frequency
- Once daily
- Duration
- 8 to 12 weeks
Forum-typical, unvalidated. The autoimmune and pro-tumor double-edge makes chronic systemic dosing the highest-risk way to use this peptide.
Higher injectable (grey-market, discouraged) Anecdotal
- Dose
- 200 to 400 mcg
- Frequency
- Once daily
- Duration
- 8 to 16 weeks
Pushing the dose runs straight into the narrow cytotoxic window and the inverted-U lesson from the topical trial. There is no rationale to go this high.
How this score is calculated →
What are the benefits of LL-37 (Cathelicidin)?
Upside contribution: 1.76
| Dimension | Weight | Score | Visual | Weighted |
|---|---|---|---|---|
| Efficacy | 25% | 2.8 | 0.700 | |
| Breadth | 15% | 3.2 | 0.480 | |
| Evidence | 25% | 2.5 | 0.625 | |
| Speed | 10% | 3.0 | 0.300 | |
| Durability | 10% | 2.0 | 0.200 | |
| Bioindividuality | 15% | 3.0 | 0.450 | |
| Total | 2.755 |
Upside Rationale
The upside comes almost entirely from mechanism plus one real human result, not from a deep clinical record. LL-37's strongest asset is breadth: a single peptide that kills microbes, dismantles biofilms, neutralizes bacterial toxins, recruits immune cells, and drives wound repair and new blood vessels. The single best human result that supports it is the topical leg-ulcer trial, per Gronberg 2014, where the lowest doses cut ulcer area by roughly 68 and 50 percent. The hard boundary is that nearly all of this depth is mechanistic or observational, and the systemic injectable use that grey-market vendors sell has no human efficacy data at all. That gap is why efficacy and evidence score in the middle of the range despite a remarkable biology, and it is the reason a peptide this versatile still cannot climb out of caution on the strength of mechanism alone.
The lowest topical dose healed venous leg ulcers best while the highest dose did no better than placebo, an inverted-U pattern that is the clearest single lesson in the whole LL-37 record: with this peptide, more is not better.Nick Urban on the venous leg-ulcer trial
Efficacy (2.8/5.0): The one quantified human therapeutic effect is genuinely good, which is the only reason efficacy is not lower. In a first-in-human topical trial of 34 people with hard-to-heal venous leg ulcers, LL-37 at its lowest two concentrations cut ulcer area by roughly 68 and 50 percent and healed several times faster than placebo, per Gronberg 2014. That is a large surrogate effect. Three things hold the score down. It is one small unreplicated trial. It used surrogate endpoints like healing-rate constants and area, not hard outcomes. And the highest dose did no better than placebo, an inverted-U pattern that means the effect is fragile and dose-sensitive. For the injectable systemic use most buyers want, human efficacy data is simply zero.
Breadth of Benefits (3.2/5.0): Breadth is the strongest dimension because LL-37 touches an unusual number of systems with at least mechanistic backing. It disrupts microbial membranes and is bactericidal against Staphylococcus aureus biofilms with a greater than 4-log kill in the lab, per Kang 2019. It neutralizes bacterial LPS and recruits immune cells, per Ciornei 2005. It also drives wound re-epithelialization and induces new blood vessels through endothelial receptors, per Koczulla 2003. The boundary is that breadth of mechanism is not breadth of proof. In humans, only wound healing has a controlled endpoint, so the rest is potential rather than demonstrated benefit.
Evidence Quality (2.5/5.0): Evidence is the dimension that holds the whole score back, despite a vast preclinical literature. There is exactly one human therapeutic trial, the topical ulcer study, per Gronberg 2014, and one phase-1 melanoma trial known only through a toxicity case report, per Dolkar 2018. Everything else is in-vitro, animal, or human observational. The ulcer trial was also industry-sponsored and never confirmed in a phase-3. So while the mechanistic base is enormous, the interventional human base is one small trial. A single tested topical use cannot carry the systemic claims people make, which is why this sits below the midpoint.
Speed of Onset (3.0/5.0): Speed is a relative bright spot, at least locally. In healing skin, LL-37 is induced within days and peaks about two days after injury, per Heilborn 2003, and its antimicrobial and biofilm-killing action is rapid in the lab. So the local pharmacology acts quickly. The honest caveat is that fast local action is not the same as fast systemic benefit, and there is no human timeline for any injectable use. The wound-healing trial measured effects over weeks of twice-weekly application, so even the proven route is a repeat-dosing, multi-week effect rather than an overnight one.
Durability (2.0/5.0): Durability is low because any benefit fades fast without repeat dosing. LL-37 is a small peptide that is broken down quickly and is partly inhibited by serum, per Ciornei 2005, so an applied or injected effect is transient by design. Endogenous LL-37 also rises and falls with infection, inflammation, and wounding, then declines as a wound closes, per Heilborn 2003. There is no depot formulation and no evidence of lasting change after dosing stops. This is a maintain-to-keep-it tool, not a one-and-done reset.
Bioindividuality Upside (3.0/5.0): Response varies enough that some people would plausibly notice far more than others. The biggest modifier is vitamin-D status, since the body's own cathelicidin depends on it, per Liu 2006. Inflammatory tone, receptor expression, and especially autoimmune predisposition all shift how LL-37 behaves in a given person. That last one matters most: someone with a psoriasis or lupus background sits at the dangerous end of the curve, while someone with none may simply see local antimicrobial effects. Predictable modifiers exist, which lifts this to average, but they cut toward risk as much as benefit.
What are the risks & downsides of LL-37 (Cathelicidin)?
Downside contribution: 2.24 (safety risks weighted extra)
| Dimension | Weight | Score | Visual | Weighted |
|---|---|---|---|---|
| Safety | 30% | 3.3 | 0.990 | |
| Side effects | 15% | 3.0 | 0.450 | |
| Cost | 5% | 2.8 | 0.140 | |
| Effort | 5% | 3.0 | 0.150 | |
| Opportunity | 5% | 3.0 | 0.150 | |
| Dependency | 15% | 2.0 | 0.300 | |
| Reversibility | 25% | 2.0 | 0.500 | |
| Total | 2.680 | |||
| Harm subtotal × 1.4 | 3.136 | |||
| Opportunity subtotal × 1.0 | 0.440 | |||
| Combined downside | 3.576 | |||
| Baseline offset (constant) | −1.340 | |||
| Effective downside penalty | 2.236 |
Downside Rationale
The downside is dominated by one thing that sets LL-37 apart from gentler immune peptides: a real, well-documented double-edge. The dominant risk is not acute toxicity at a single dose but the cumulative, context-dependent harm of feeding more of a molecule that is a confirmed autoimmune trigger and a documented cancer growth factor. The people most exposed are those with any psoriasis, lupus, rheumatoid arthritis, or cancer history, where the mechanism that helps in one setting is the same one that hurts in another. This concern is intrinsic to the LL-37 molecule itself, not just a supply-chain problem, which is why safety carries the heaviest weight in the downside picture. On top of that sit a genuine side-effect profile from its narrow toxic window, a real opportunity cost against better-studied immune and repair peptides, and the unregulated sourcing that comes with any research-chemical purchase.
Safety Risk (3.3/5.0): The reason safety scores upper-middle is the intrinsic double-edge, not a clean catastrophic floor. The first edge is autoimmunity. LL-37 binds self-DNA to drive the interferon response that initiates psoriasis, per Lande 2007, and it is a T-cell autoantigen recognized in about 46 percent of psoriasis patients, per Lande 2014, with reviews extending the link to lupus and rheumatoid arthritis, per Kahlenberg 2013. Injecting more of a confirmed self-trigger into someone primed for autoimmune disease is the single biggest reason this peptide caps in caution.
The second edge is cancer. LL-37 is a documented growth factor that raised lung cancer cell proliferation at just 5 ng/mL, per von Haussen 2008, and it drove ovarian tumor progression where neutralizing it slowed growth, per Coffelt 2009. The effect is context-dependent and can even be tumor-suppressive in some tissues, per Prevete 2015, so this is a real, cumulative concern rather than a single-dose disaster. There is no human safety study of exogenous systemic LL-37 in anyone, let alone autoimmune-prone or cancer-history users.
Side Effect Profile (3.0/5.0): The side-effect profile for LL-37 is meaningful and partly intrinsic to how the peptide works, which the human and lab evidence makes clear. LL-37 is cytotoxic and hemolytic to host cells at the upper end of its concentration range, through the same membrane interactions that kill bacteria, per Ciornei 2005, which gives it a narrow therapeutic window where the dose that helps locally can damage your own cells systemically. Because LL-37 is an alarmin, pro-inflammatory and flu-like flares are mechanistically expected rather than surprising. The one human melanoma study documented a real dermatologic toxicity, with verrucous papules and a blistering eruption that resolved only after stopping, per Dolkar 2018. Forum reports of injection-site reactions and skin flares fit that same picture. Importantly, the topical ulcer doses were well tolerated, so route and dose matter enormously here.
Financial Cost (2.8/5.0): Cost is moderate and ongoing rather than extreme. Research-chemical vials are not especially expensive per unit, but any benefit needs repeat dosing, which turns a real attempt into a recurring monthly spend. The bigger cost framing is the risk premium of buying an unapproved peptide with no quality guarantee, where you are paying for material whose purity and identity you cannot verify.
Time/Effort Burden (3.0/5.0): Effort is non-trivial for the injectable route, and even the evidence-backed route is hands-on. Using LL-37 by injection requires reconstitution with bacteriostatic water, daily subcutaneous dosing, careful cold storage, and dose titration, which is a real logistics load compared with swallowing a pill. The only route with study support, topical wound care, is simpler but still means repeat application over several weeks to mirror the trial schedule. Either way, LL-37 is a hands-on, ongoing protocol rather than a passive one you can set and forget.
Opportunity Cost (3.0/5.0): Opportunity cost is genuine because better-studied options exist for most of the goals people chase here. For immune support, correcting vitamin D raises your own cathelicidin through the proven pathway, per Liu 2006, with none of the injection risk. For repair and gut goals, peptides like the one in the BPC-157 report at https://outliyr.com/reports/bpc-157/ or the gentler tripeptide in the KPV report at https://outliyr.com/reports/kpv/ have broader track records and no autoimmune or cancer signal. Money and effort spent chasing unproven systemic LL-37 could go to those or to basic anti-infective and wound-care options with real evidence.
Dependency/Withdrawal (2.0/5.0): Dependency risk is low. LL-37 is an endogenous peptide with a transient effect, so there is no addiction or withdrawal syndrome, and stopping simply lets levels return to whatever your own biology produces. The score is not lower only because chronic supraphysiologic exposure to an immune-active molecule is poorly characterized, so the safest assumption is mild caution rather than a clean zero.
Reversibility (2.0/5.0): Reversibility is mostly good but not guaranteed, which is the key nuance. The peptide itself clears quickly once you stop, so the molecule does not linger. The catch is that an autoimmune flare it sets off may not reverse on the same timeline. If LL-37 helps trigger a psoriatic or interferon-driven response, per Lande 2007, that process can persist after the peptide is gone. So clearance is fast, but the downstream immune consequence is the part that may not cleanly undo.
The honest verdict on LL-37 is that it is worth watching and studying, not worth injecting based on what we know today. The mechanism is real, the topical wound result is real, and the double-edge is real too.Nick Urban, Outliyr immune-peptide reports
Is LL-37 (Cathelicidin) worth it?
The practical verdict is simple: LL-37 is a fascinating molecule with one promising topical use and a genuine double-edge, which is exactly why it sits in caution rather than higher. If you are drawn to it, the only route with human evidence is topical wound care, and even that rests on one small trial of 34 people. For the injectable systemic use the grey market sells, you would be dosing a confirmed autoimmune trigger and documented cancer growth factor with zero human efficacy data behind it, which is a poor trade no matter how good the mechanism reads. The score reflects that balance honestly: a rich, broad mechanism pulled down by thin human proof and a real intrinsic risk that lands hardest on people with any autoimmune or cancer history. Watch the research closely, but do not mistake an impressive mechanism for a proven therapy.
✅ Best for: Researchers and clinicians who want to understand a uniquely versatile host-defense peptide and its role in immunity, wound healing, and disease. People specifically interested in topical wound care who accept that the evidence is one small trial and that the lowest dose worked best, per Gronberg 2014. People who would rather raise their own cathelicidin the proven way, by correcting vitamin D, per Liu 2006. Anyone with no autoimmune or cancer history who still wants to follow this peptide's science closely before any use.
❌ Avoid if: You have any personal or family history of psoriasis, lupus, or rheumatoid arthritis, since LL-37 is a confirmed autoimmune trigger and autoantigen, per Lande 2014. You have any active, prior, or suspected cancer, since it is a documented growth factor for lung, ovarian, and breast cancer cells, per von Haussen 2008. You want a proven systemic immune or repair peptide, because human efficacy data for injectable LL-37 is zero. You cannot verify source quality, since it is sold unregulated as a research chemical with no purity or sterility guarantee.
What is LL-37 (Cathelicidin) best for?
The overall BioHarmony score reflects the intervention's primary evidence profile. These subratings are independent assessments per use case.
| Use Case | Score | Summary |
|---|---|---|
| ○ Immune Function Primary | 3.7 | Immune function is LL-37's native job and the mechanism is genuinely deep, but the human therapy data is thin. It kills microbes by punching holes in their membranes, neutralizes bacterial LPS, and recruits immune cells, per Ciornei 2005, and its induction tracks vitamin-D status and tuberculosis defense, per Liu 2006. The score sits in the middle because all of that is mechanistic and observational. No human trial shows that injecting extra LL-37 improves infection outcomes, and the same immune machinery can turn against you in the autoimmune context. |
| ○ Wound Healing Primary | 4.2 | Wound healing is the one use case with real human evidence, which is why it scores highest. In a first-in-human topical trial of 34 people with hard-to-heal venous leg ulcers, LL-37 at the lowest two concentrations cut ulcer area by roughly 68 and 50 percent and healed several times faster than placebo, per Gronberg 2014. Mechanism backs this up: LL-37 is strongly induced in healing skin, peaks about two days after injury, and is missing from the edge of chronic ulcers, per Heilborn 2003. The cap below five reflects that this is one small, unreplicated, surrogate-heavy trial, and the highest dose did no better than placebo. |
Frequently Asked Questions
What is LL-37 and how does it work?
LL-37 is the only human cathelicidin, a small host-defense peptide cut from the hCAP-18 precursor and induced by vitamin D, infection, and wounding. It kills microbes by punching holes in their membranes, breaks up biofilms, neutralizes bacterial LPS, and recruits immune cells, per Ciornei 2005. It also drives wound re-epithelialization and new blood vessels, per Koczulla 2003. It is a single helix doing many jobs at once.
Does LL-37 actually break up biofilms?
In the lab, yes. LL-37 was bactericidal against established Staphylococcus aureus biofilms, producing a greater than 4-log drop in viable bacteria and outperforming the other agents tested, per Kang 2019. That in-vitro result drives most self-experimentation for chronic infection and gut biofilms. The honest caveat is that no human study has shown culture-confirmed clearance, and serum partly inhibits LL-37's antimicrobial action, per Ciornei 2005.
What human evidence actually exists for LL-37?
The honest answer is one small topical trial. In 34 people with hard-to-heal venous leg ulcers, topical LL-37 at its lowest two doses cut ulcer area by about 68 and 50 percent and healed faster than placebo, with the highest dose no better than placebo, per Gronberg 2014. A separate melanoma trial is known only through a toxicity case report, per Dolkar 2018. For injectable systemic use, human efficacy data is zero.
Can LL-37 trigger autoimmune disease like psoriasis?
Yes, and this is the headline risk. LL-37 binds self-DNA released from dying cells and turns it into a trigger that drives the interferon response initiating psoriasis, per Lande 2007. It is also a confirmed T-cell autoantigen, recognized by immune cells in roughly 46 percent of psoriasis patients, per Lande 2014. Reviews tie it to lupus and rheumatoid arthritis too, per Kahlenberg 2013. Injecting more of a self-trigger is a real concern.
Is LL-37 linked to cancer growth?
LL-37 is a documented growth factor for several cancers, which is why a cancer history is a stop signal. It acted as a growth factor for lung cancer cells at just 5 ng/mL, per von Haussen 2008, and drove ovarian tumor progression where neutralizing it slowed growth, per Coffelt 2009. The effect is context-dependent and in some tissues LL-37 can be tumor-suppressive, per Prevete 2015, but the pro-tumor signal is well documented.
How do people dose LL-37, and is it safe to inject?
There is no approved dose for any route. The only evidence-based route is topical, where the lowest concentration healed best and the highest did no better than placebo, an inverted-U pattern, per Gronberg 2014. Grey-market injectable ranges of roughly 100 to 400 mcg daily are vendor and forum lore with no human safety or efficacy basis. LL-37 is also cytotoxic and hemolytic at the high end of its range, per Ciornei 2005, so escalating the dose is actively risky.
Who should avoid LL-37?
Anyone with a personal or family history of psoriasis, lupus, or rheumatoid arthritis should avoid systemic LL-37, because it is a confirmed autoimmune trigger and autoantigen, per Lande 2014. Anyone with active, prior, or suspected cancer should avoid it too, since it is a growth factor for several tumor types, per von Haussen 2008. With no long-term human safety data for injection, chronic systemic dosing is the highest-risk way to use it.
What is the vitamin D connection to LL-37?
Vitamin D is the main natural lever for your own LL-37. The CAMP gene that makes cathelicidin is a vitamin-D-receptor target, and immune activation only induces LL-37 to kill intracellular tuberculosis when vitamin D is sufficient, per Liu 2006. Low vitamin D blunts that response. This is the mechanism behind the idea that vitamin D supports immunity, and it is the lower-risk way to influence cathelicidin compared with injecting the peptide.
How fast does LL-37 work and how long does it last?
Locally it acts fast but it does not last. In healing skin, LL-37 is induced within days and peaks about two days after injury, per Heilborn 2003, and its antimicrobial action is rapid in the lab. The catch is durability: LL-37 is a small peptide that is broken down quickly and partly inhibited by serum, per Ciornei 2005. Any benefit depends on repeat application, and there is no depot or lasting-effect data.
What could change LL-37 (Cathelicidin)'s score?
BioHarmony scores are living assessments. New research, regulatory changes, or personal context can shift the score up or down. These are the most likely scenarios that would change this intervention's rating.
The fastest way up is real human therapeutic data, and the fastest way down is a documented harm signal in actual users. Because the current LL-37 score rests on one small topical trial plus a strong but intrinsic risk story, even modest new human evidence in either direction would move it more than usual. A confirmatory wound-healing trial would lift efficacy and evidence together and could nudge LL-37 into neutral territory. On the other side, a clinical autoimmune-flare or tumor-promotion signal in people using exogenous LL-37 would raise the safety dimension sharply and push the score toward skip. The single biggest unknown is what systemic injectable dosing actually does in humans, since that use has zero trial evidence today, so the first credible human safety study of that route is the result most likely to settle the question in either direction.
| Scenario | Dimension shifts | New Score |
|---|---|---|
| A larger confirmatory topical wound-healing trial replicates the leg-ulcer result | Efficacy 2.8 to 3.4, Evidence 2.5 to 3.2 | 4.9 / 10 ⚖️ Neutral |
| A published melanoma phase-1 shows real anti-tumor efficacy with manageable safety | Efficacy 2.8 to 3.2, Evidence 2.5 to 3.0 | 4.8 / 10 ⚖️ Neutral |
| A human trial of systemic LL-37 shows a clean safety profile | Safety 3.3 to 2.6, Evidence 2.5 to 2.9 | 4.9 / 10 ⚖️ Neutral |
| A clinical autoimmune-flare signal emerges in exogenous LL-37 users | Safety 3.3 to 4.0, Reversibility 2.0 to 2.6 | 4.1 / 10 ⚠️ Caution |
| A tumor-promotion signal is documented in people using injectable LL-37 | Safety 3.3 to 4.2, Side Effects 3.0 to 3.4 | 4.1 / 10 ⚠️ Caution |
| Independent testing keeps finding mislabeled or contaminated product | Safety 3.3 to 3.6, Bioindividuality 3.0 to 2.6 | 4.4 / 10 ⚠️ Caution |
Key Evidence Sources
- Gronberg 2014, Wound Repair Regen: topical LL-37 was safe and healed hard-to-heal venous leg ulcers in a first-in-human trial of 34 people, with the lowest doses cutting ulcer area about 68 and 50 percent and the highest dose no better than placebo.. The single positive human therapeutic RCT (topical, n=34); inverted-U dose response.
- Dolkar 2018, J Cutan Pathol: dermatologic toxicity case report from a phase-1 intratumoral LL-37 trial in a melanoma patient, with local lesion shrinkage but a verrucous and vesiculobullous eruption.. Confirms a real melanoma trial existed; published only as a 2018 toxicity case, not an efficacy paper.
- Lande 2014, Nat Commun: LL-37 is a T-cell autoantigen in psoriasis, recognized by circulating T cells in about 46 percent of patients.. This 2014 study establishes LL-37 as a defined T-cell autoantigen; central to the autoimmunity concern.
- Lande 2007, Nature: plasmacytoid dendritic cells sense self-DNA bound to LL-37, triggering interferon and initiating psoriasis.. The 2007 self-DNA study; mechanism by which LL-37 breaks tolerance to self.
- Kahlenberg 2013, J Immunol: review placing LL-37 in the pathogenesis of lupus, rheumatoid arthritis, and atherosclerosis.. 2013 review extending the autoimmunity link beyond psoriasis.
- von Haussen 2008, Lung Cancer: LL-37 acts as a growth factor for lung cancer cells, increasing proliferation at 5 ng/mL via EGFR signaling.. Primary pro-tumor evidence in lung cancer; documents a 2008 growth-factor effect.
- Coffelt 2009, PNAS: pro-inflammatory LL-37 promotes ovarian tumor progression by recruiting mesenchymal stromal cells, and neutralizing LL-37 inhibits tumor growth.. In-vivo ovarian pro-tumor evidence from a 2009 study; neutralization slows growth.
- Coffelt 2008, Int J Cancer: ovarian cancers overexpress hCAP-18, and recombinant LL-37 increases proliferation, chemotaxis, and invasion of ovarian cancer cells.. Earlier 2008 ovarian overexpression and invasion study supporting the cancer concern.
- Prevete 2015, Oncogene: the FPR1 receptor exerts a tumor-suppressor function in gastric cancer, the honest counter-context to LL-37's pro-tumor signaling.. This 2015 study is counter-context showing the cancer effect is tissue and context dependent.
- Ciornei 2005, Antimicrob Agents Chemother: LL-37 neutralizes LPS and is chemotactic, but is cytotoxic and hemolytic to host cells and partly inhibited by serum.. Primary 2005 source for LPS neutralization, host-cell cytotoxicity, and serum inhibition.
- Koczulla 2003, J Clin Invest: LL-37 is angiogenic, inducing new blood vessels through endothelial FPRL1, with impaired wound vascularization in cathelicidin-deficient mice.. 2003 angiogenesis and wound-vascularization mechanism study.
- Heilborn 2003, J Invest Dermatol: LL-37 is induced in healing skin, peaks about two days after injury, and is absent from chronic ulcer edge epithelium.. 2003 wound re-epithelialization study; supports the wound-healing use case.
- Liu 2006, Science: immune activation induces vitamin-D-dependent cathelicidin to kill intracellular tuberculosis, and low vitamin D blunts the response.. 2006 vitamin-D induction study; basis for the vitamin-D-and-immunity link.
- Kang 2019, PLoS One: LL-37 is bactericidal against established Staphylococcus aureus biofilms, with a greater than 4-log reduction in viable bacteria.. 2019 in-vitro biofilm study; the antibiofilm evidence behind self-experimentation.
What does the evidence say about LL-37 (Cathelicidin)?
Evidence on this intervention is summarized across three complementary streams: contemporary clinical research, pre-RCT-era pharmacology and observational use, and the traditional medical systems that documented it first. Convergence across streams signals higher confidence; divergence is surfaced honestly.
Modern Clinical Research
Confidence: Low
Citations: Gronberg 2014, Lande 2014, Coffelt 2009
What to Track If You Try This
These are the data points that matter most while running a 30-day Experiment with this intervention.
How to read this section
- Pre
- Test or score before starting the protocol. Anchors a baseline.
- During
- Track while running the protocol so you can see if anything is changing.
- Post
- Re-test after a full cycle to confirm the change held.
- Up
- The marker should rise. For most positive outcomes, that is a good sign.
- Down
- The marker should fall. For most positive outcomes, that is a good sign.
- Stable
- The marker should hold steady. Big swings in either direction are a yellow flag.
- Watch
- Direction depends on dose, timing, and your baseline. Pay close attention to the trend.
- N/A
- No expected direction. The entry is there to anchor a baseline reading.
- Primary
- The Pulse dimension most likely to shift. Track this first.
- Secondary
- Also relevant, but a smaller or less consistent shift. Track if Primary is unclear.
Bloodwork to Order
Open These Markers In Your Dashboard
- CRP Pre | Expected Watch During | Expected Watch
- Vitamin D Pre | Expected Watch
Pulse Dimensions to Watch
- Body During | Expected Watch | Primary
- Energy During | Expected Watch | Secondary
- Calm During | Expected Watch | Tertiary
Subjective Signals (Daily Voice Card)
- New or worsening skin flare, rash, or red scaly patches Scale 1-5 | During | Expected Watch
- Injection-site reaction or flu-like inflammatory feeling after a dose Scale 1-5 | During | Expected Watch
Red Flags: Stop and Consult
- Any personal or family history of psoriasis, lupus, or rheumatoid arthritis: do not use systemically; LL-37 is a confirmed autoimmune trigger and autoantigen.
- Any active, prior, or suspected cancer: avoid; LL-37 is a documented growth factor for several tumor types.
- A new or worsening skin flare, rash, or scaly plaque after starting: stop immediately, since this can reflect the psoriasis-linked mechanism.
- Persistent flu-like inflammation, fever, or spreading injection-site reaction: stop and consult a clinician.
Other interventions for Immune Function
See all ratings →📊 How BioHarmony scoring works
BioHarmony translates a weighted expected-value calculation into a reader-facing 0–10 score. Tier bands: Skip 0–3.6, Caution 3.7–4.7, Neutral 4.8–5.7, Worth Trying 5.8–6.9, Strong Recommend 7.0–7.9, Top-tier 8.0+.
Harm-type downsides (safety risk, side effects, reversibility, dependency) carry a 1.4× precautionary multiplier. Harm weighs more than benefit. Opportunity-type downsides (financial cost, time/effort, opportunity cost) are subtracted at face value.
Use case subratings are independent assessments of how well the intervention addresses specific health goals. They are not components of the overall score. Each subrating reflects the scorer's judgment based on use-case-specific evidence, safety, and effect sizes.
Every dimension is evaluated on a 1–5 scale, and the baseline (1) is subtracted before weighting. A perfect intervention with zero downsides contributes zero penalty rather than a residual floor, so top-tier scores are actually reachable.
EV = Upside − Downside
EV = 1.755 − 2.236 = -0.481
Formula v0.5 maps EV = 0 to score 5.0. Above neutral, 1 EV point equals 1 score point. Below neutral, 1 EV point equals about 0.71 score points, so EV = −7 reaches 0.0 while EV = +5 reaches 10.0. Both sides use the full 5-point half-scale.
Score = 5 + (-0.481 / 7) × 5 = 4.7 / 10
