The role of
antimicrobial peptides is particularly important in the oral cavity where there is constant challenge by microorganisms. The
alpha-defensins are a group of cationic
peptides that comprise 30-50% of the total
protein in azurophilic granules of human neutrophils. They include the human neutrophil
peptides (HNP) 1, 2 and 3 which have almost identical amino acid sequences but differ in their
biological activities. The amino acid sequence similarities of the
defensins have made it difficult to unequivocally determine the presence of individual
defensins using antibody-based techniques. However, by virtue of their cationic nature we postulated that the
defensins would fly particularly well in mass spectrometry and that this characteristic would allow facile identification of individual HNPs in unfractionated gingival crevicular fluid (GCF) from
periodontitis patients and healthy controls. Although there was variability in levels of
defensins detected in periodontal health and disease,
HNP-1 was always identified as the major peak in the triad and
HNP-3 as the minor peak, lending support to the hypothesis that
HNP-2 may arise by post-translational proteoyltic cleavage of
HNP-3 rather than
HNP-1. The finding that the
defensins were more abundant in a higher proportion of the healthy sites studied could be linked to a more intact
defensin barrier in periodontal health.