LL-37 (Human Cathelicidin) LL-37 is the sole cathelicidin-derived host?defense peptide in humans. As a cationic amphipathic peptide, it destructs pathogen cell membranes to deliver broad?spectrum activity against Gram-positive, Gram-negative bacteria, fungi and selected enveloped viruses, and exhibits strong biofilm-disrupting capacity. It mediates immune homeostasis via LPS endotoxin neutralization, immune cell chemotaxis and inflammatory response modulation. It supports keratinocyte migration to accelerate wound closure and maintains skin and mucosal barrier function.