LL-37 is the sole human cathelicidin—a 37-amino-acid cationic peptide named for two N-terminal leucines and chain length. It is produced by neutrophils, macrophages, and epithelial cells of skin, lung, and gut—where the body meets pathogens directly. The primary antimicrobial mechanism is electrostatic: the molecule’s net +6 charge attracts negatively charged bacterial membranes; the peptide inserts, forms transmembrane pores, and lyses the cell. Coverage spans Gram-positive and Gram-negative bacteria, fungi, and several viruses, including enveloped types.
Beyond direct pathogen killing, LL-37 coordinates immunity: it neutralizes bacterial LPS, limiting excessive endotoxin response, and chemoattracts neutrophils, monocytes, mast cells, and T lymphocytes to the infection site. It activates epithelial cells via the MAPK/ERK pathway, increasing IL-8 and driving proliferative and migratory responses—making it both defensive and regenerative for barrier tissues. Antibiofilm activity stands out separately: LL-37 disrupts mature S. aureus and P. aeruginosa biofilms and prevents formation—a mechanism often resistant to standard antibiotics in chronic infection.
LL-37’s immunomodulatory role is dual and context-dependent: at physiological concentrations it lowers TLR4-dependent inflammation and IL-10, while at high concentrations or in certain microenvironments it can amplify pro-inflammatory signals and type I IFN. Use therefore requires understanding inflammatory context and baseline immune status. Potential in oncology (immune activation in solid tumors) and chronic skin conditions (atopic dermatitis, psoriasis) is under active study.
🛡️ Antimicrobial spectrum (bacteria, fungi, viruses): ★★★★★
🔥 Immune coordination and chemotaxis: ★★★★☆
🧬 Antibiofilm activity: ★★★★★
✅ Safety: ★★★☆☆ (dual immune profile requires context assessment)
⚠️ Possible sensations and side effects: possible flare in inflammatory states; systemic use warrants caution
🤝 Combinations (goal → stack)
🛡️ Immune defense + infection → LL-37 + Thymosin Alpha 1
🧬 Chronic infection + biofilm → LL-37 + KPV
🫁 Respiratory protection → LL-37 + Bronchogen
| CAS number | 154947-66-7 |
| Batch purity | 99.49 % |
Full details in our guide
https://peptideboost.club/guide/ll-37
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