LL-37 is the only human cathelicidin antimicrobial peptide, expressed by neutrophils, epithelial cells, and other immune cells.
Mechanism — Disrupts microbial membranes (bacteria, fungi, enveloped viruses) and modulates immune signaling. Also has wound-healing and anti-inflammatory roles. Vitamin D upregulates endogenous LL-37 expression.
Use case — Investigational for biofilm-associated infections (chronic Lyme, mold-related illness, Bartonella, sinus biofilms). Often paired with thymosin alpha-1. Research dosing 100-500 mcg subcutaneous daily, cycled.
Caveats — Investigational and expensive. Stack carefully — concurrent immunosuppression negates the rationale. Skin reactions at injection sites are common.