← Shelf·Human cathelicidin peptide·XXVII.
LL-37.
The 37-amino-acid mature peptide cleaved from human cathelicidin antimicrobial protein (hCAP-18), encoded by the CAMP gene. The only cathelicidin in humans. Broadly characterized since the 1990s for direct antimicrobial activity and, later, for immunomodulatory signaling through formyl-peptide receptor 2 (FPR2) and other receptors.
Your body already makes LL-37 — neutrophils, epithelial cells, and keratinocytes upregulate it in response to injury and infection. This is a synthetic version of the same sequence, laboratory-produced to a research-grade specification.
Sold across gut-health and inflammation products with implications the direct-injection literature has not confirmed for consumer use. LL-37 is a legitimate immunology research compound with a well-mapped mechanism. The consumer marketing narrative substantially outruns the trial evidence.
Straight talk
Straight talk: LL-37 biology is well-characterized in cell-culture and animal models — antimicrobial, chemotactic, immunomodulatory effects are all published. Human trials of injectable LL-37 as sold are essentially absent. Complicating the picture: LL-37 has both anti-inflammatory and pro-inflammatory effects depending on context, and elevated LL-37 has been implicated in the pathogenesis of some inflammatory conditions (psoriasis, lupus). It is a real molecule with a genuinely mixed clinical story.
What the research studies
The literature, not a summary of it.
Foundational cathelicidin work: Robert Lehrer (UCLA), Ole Sørensen, Michael Zasloff. Contemporary LL-37 signaling: Richard Gallo (UCSD), John Niederhauser. Journals: J Immunol, J Biol Chem, Nature, J Clin Invest. Read the research yourself:
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≥ 99% by HPLC on the current lot — ILS Laboratories (ISO/IEC 17025).
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