LL-37

LL-37 is the only human cathelicidin antimicrobial peptide (CAMP), a 37-amino acid peptide cleaved from the precursor protein hCAP18. It serves as a first-line innate immune defense against bacteria, viruses, and fungi. It also disrupts biofilms — the protected bacterial communities that resist conventional antibiotics.

Disrupts microbial membranes via electrostatic interaction with negatively charged bacterial phospholipids, forming pores that lyse bacteria. Penetrates and disperses biofilms by disrupting their polysaccharide matrix. Also acts as a chemokine — recruiting neutrophils, monocytes, and T-cells. Modulates TLR signaling, promotes angiogenesis in wound healing, and can neutralize endotoxin (LPS).

Plasma half-life approximately 2 hours due to proteolytic degradation. Rapidly distributed to tissues, particularly sites of infection or inflammation. Local tissue concentrations may persist longer than plasma levels. Typically dosed subcutaneously, 50–100 mcg.

Antimicrobial activity (broad-spectrum), biofilm disruption, wound healing, chronic infections (Lyme, CIRS), immune modulation, anti-inflammatory effects, cancer immunology.

Extensively studied in vitro and in animal models. Phase 1–2 clinical trials for chronic wounds (OP-145, a derivative). Used off-label for chronic infections. No FDA-approved therapeutic formulation of LL-37 itself.

• LL-37 — human cathelicidin review — FEMS Microbiology Letters · doi.org
• LL-37 biofilm disruption — PLoS One · pubmed.ncbi.nlm.nih.gov
• Cathelicidin antimicrobial peptides review — J. Leukocyte Biology · doi.org
• LL-37 stability and tissue distribution · doi.org