Podcast episode 96 (in German)
LL-37 – the body’s own antibiotic
October 4, 2026
LL-37 is not an invented molecule but the only cathelicidin the human body produces. The studies used to advertise it concern open wounds — what is on offer is the injection. There is more than one step in between.
What it is about
The peptide of 37 amino acids sits in neutrophil granulocytes and does three well-documented things there: it tears holes in microbial membranes, attracts further immune cells and supports wound healing. The basic research on this is strong, and there is even a real link to the vitamin D receptor, which switches on the corresponding gene. The episode reads the human studies closely — they are studies on open wounds, with the substance applied as a dressing — and then moves to the point that appears on no sales page: in a common skin disease, the same molecule is a recognized autoantigen targeted by the immune system.
Key points
- LL-37 consists of 37 amino acids and is the only cathelicidin the human body produces; other animals have whole families of them.
- The larger wound study randomized 149 patients at 15 centers over 13 weeks, blinded, placebo-controlled and with 2 concentrations.
- The primary endpoint results practically overlap: 26.5 and 24.7 percent in the active groups versus 25.3 percent under placebo.
- In the subgroup with wounds of 10 square centimeters or more, 28.1 percent closed completely versus 8.1 percent under placebo.
- The higher of the 2 tested concentrations reached only 19.6 percent in exactly this subgroup — the pattern a real effect would lead you to expect is missing.
- For injected LL-37 in humans there are 0 long-term data, no approval and no long-term safety monitoring.
- The score stands at human evidence 1, safety 1, use 1 and hype 1 — the lowest row in the series, of all things for the best basic research.
Where the data stop
Between the studies and the offer lies a double leap: from wound dressing to injection, and from a wound on the leg to the whole body. For injected use there are no human data and no approval. What is well described, by contrast, is a mechanism in the other direction: in psoriasis, LL-37 is a recognized autoantigen. It binds to the body’s own DNA, and via a receptor for pathogen genetic material this complex triggers an interferon response that stands at the onset of the disease. In rosacea, an overactive enzyme cuts the molecule into fragments that are more pro-inflammatory than the intact peptide.
Two further open points: the effect on tumors is described as tissue-dependent, sometimes promoting, sometimes inhibiting, and the peptide promotes the formation of new blood vessels. And at higher concentrations it also attacks human cells — in the body, its release is tightly regulated by location, amount and duration.
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Published on October 4, 2026.
The topic in the database
- The body’s own defense classic: the only human cathelicidin, with broad antimicrobial activity and a role in immune modulation.LL-37
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Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in the hands of a physician. Last updated: 2026-09-19.