Identification of a proline-arginine-rich antibacterial peptide from neutrophils that is analogous to PR-39, an antibacterial peptide from the small intestine.

Neutrophil nonoxidative defense mechanisms include several low molecular weight antimicrobial peptides. We have isolated a proline-arginine-rich antibacterial peptide from porcine neutrophils. This cationic, low molecular weight peptide has a very high degree of identity (97%) to a bactericidal peptide, PR-39, that has been found in the porcine small intestine. Isolation of the same antimicrobial peptide from both neutrophils and cells of the small intestine in the same species is unique and suggests an important role for this protein in innate immune defenses.