Peptide directorySkin, immune & repair

HNP-3

HNP-1 with one residue changed, from a neighbouring gene copy.

Where it comes from

Made in
Neutrophil granules
Sent out by
With HNP-1 and HNP-2
Acts on
  • Bacteria, fungi, enveloped viruses
  • Immune cells

What it does

  • Kills microbes much as HNP-1 does
  • About one person in ten carries no DEFA3 copy at all and makes no HNP-3 2
  • Studied in the same breath as HNP-1 and HNP-2, because no assay in common use separates them 1

In medicine

  • Nothing of its own. The immunoassays used in research report HNP-1, HNP-2 and HNP-3 together as HNP1-3, so no measurement in people is of HNP-3 alone 1
  • It has never been given as a medicine, and no trial has tested it apart from the other neutrophil defensins

Beyond the body’s own use

  • Chromatography and mass spectrometry tell it from HNP-1 by the single aspartate at its start; that is how its share of the total was shown to follow gene copy number 2
  • What is unknown is whether the people without DEFA3 are at any disadvantage: copies set the ratio of HNP-1 to HNP-3, but not how much defensin a person makes in all 2

Sources

  1. Ganz et al., Defensins: natural peptide antibiotics of human neutrophils, Journal of Clinical Investigation 1985
  2. Aldred et al., Copy number polymorphism of the alpha-defensin genes DEFA1 and DEFA3, Human Molecular Genetics 2005

This card describes what a medicine is for and what the evidence says; it recommends nothing. Talk to your clinician about anything you read here.