The primary structures of peptides investigated are aligned; net overall charge is shown at right. α-Defensins are aligned by their conserved Cys residues (in bold), and their CI-CVI, CII-CIV, and CIII-CV disulfide connectivities are depicted by brackets. The α-defensins from mouse Paneth cells and rhesus neutrophils are highly cationic as compared to the human myeloid peptides, HNPs 1–3. The octadecapeptide RTD-1, a θ-defensin, is a macrocyclic peptide identified in rhesus macaque neutrophils and found only in Old World monkeys.