LL-37 [5mg]

LL-37 is the sole human cathelicidin, generated in vivo by proteolytic cleavage of the precursor protein hCAP-18 by the serine protease proteinase 3. The 37-amino acid C-terminal fragment — named for its two N-terminal leucine residues — was first characterized by Birgitta Agerberth, Gudmundur H. Gudmundsson, and colleagues at the Karolinska Institutet in Stockholm in the mid-1990s. It forms an amphipathic alpha-helix in membrane-mimetic environments.

Preclinical investigation has covered direct antimicrobial activity against gram-positive and gram-negative organisms, disruption of bacterial biofilm architecture, modulation of cytokine and chemokine signaling, neutrophil and dendritic cell responses, and wound closure dynamics in murine models. A landmark 2002 study by Scott, Davidson, Bowdish, and Hancock at the University of British Columbia demonstrated that LL-37 functions as a multifunctional modulator of innate immune signaling in vitro. All findings referenced here derive from preclinical models and have not been validated in controlled human clinical trials.