Human Alpha-Defensin 1
Evidence: CAntimicrobial / Innate-Defense Peptides
Evidence Snapshot
What this grade covers
Composite proposed grade: identity/structure B; native neutrophil expression B; pooled antimicrobial evidence C (original characterization used a pooled HNP-1/2/3 preparation); disease-association context not independently graded (all sources pooled, context-only); controlled human administration absent (no grade).
Regulatory Context
Endogenous human peptide; no native HNP-1 drug product approval record identified in this review.
Research Takeaway
Human neutrophil peptides (HNP-1, HNP-2, HNP-3), collectively termed defensins, were originally identified as small antimicrobial peptides localized to the azurophilic granules of human neutrophils.
Evidence boundary: Original antimicrobial assays used the native mixed HNP-1/2/3 preparation, not an HNP-1-isolated fraction in every experiment -- not every finding here is isolated-HNP-1-specific.
See all 3 evidence claims →Quick Summary
Human alpha-defensin 1 (HNP-1) is a neutrophil-granule-derived antimicrobial peptide, one of a closely related trio (HNP-1, HNP-2, HNP-3) sharing nearly identical structure. HNP-2 is not a separate gene product but a processing variant; HNP-3 is a distinct paralogous gene product. All disease-association evidence for this family measures the three peptides together (pooled), not HNP-1 in isolation, and no controlled human administration study of native HNP-1 has been identified.
Mechanism & Research Overview
Human alpha-defensin 1 (HNP-1) is a neutrophil-granule-derived antimicrobial peptide, one of a closely related trio (HNP-1, HNP-2, HNP-3) sharing nearly identical structure. HNP-2 is not a separate gene product but a processing variant; HNP-3 is a distinct paralogous gene product. All disease-association evidence for this family measures the three peptides together (pooled), not HNP-1 in isolation, and no controlled human administration study of native HNP-1 has been identified.
Evidence Claims
Individual scientific statements drawn from the sources cited below, each shown with the specific evidence boundary that statement does not establish.
Supported
Human neutrophil peptides (HNP-1, HNP-2, HNP-3), collectively termed defensins, were originally identified as small antimicrobial peptides localized to the azurophilic granules of human neutrophils.
Does not establish
Evidence boundary: Original antimicrobial assays used the native mixed HNP-1/2/3 preparation, not an HNP-1-isolated fraction in every experiment -- not every finding here is isolated-HNP-1-specific.
Sources: Defensins. Natural peptide antibiotics of human neutrophils
Supported
HNP-1, HNP-2, and HNP-3 share an identical 29-30-residue, three-disulfide-bond scaffold and differ from one another only in their N-terminal residue(s); HNP-2 lacks the extra N-terminal residue present in HNP-1 and HNP-3.
Does not establish
Evidence boundary: Structural paper; does not itself measure antimicrobial potency, and sequence similarity is not evidence of identical biological activity between the three.
Sources: Primary structures of three human neutrophil defensins
Supported
Elevated pooled serum levels of human neutrophil peptides (HNP1-3) have been reported in patients with lupus nephritis, Wegener's granulomatosis (ANCA-associated vasculitis), and systemic lupus erythematosus, often alongside elevated human beta-defensin 2.
Does not establish
Evidence boundary: All three sources measure POOLED HNP1-3, not isolated HNP-1. Correlative disease-association only, not causal, and not isoform-specific to HNP-1.
Sources: Human neutrophil peptide 1-3, a component of the neutrophil extracellular trap, as a potential biomarker of lupus nephritis; Altered serum levels of human neutrophil peptides (HNP) and human beta-defensin 2 (hBD2) in Wegener's granulomatosis; Elevated levels of human beta-defensin 2 and human neutrophil peptides in systemic lupus erythematosus
Safety & Evidence Limitations
Considerations reported in the sources cited on this page — not a complete list of every possible risk, and not medical advice.
Safety Consideration
Every human disease-association source located measures pooled HNP1-3, not HNP-1 specifically -- this is a permanent limitation, not a pending gap.Safety Consideration
No study administering native HNP-1 to human volunteers by any route has been identified in this evidence review.Safety Consideration
The founding antimicrobial characterization of HNP-1 used the native mixed HNP-1/2/3 preparation in most assays, not an isolated HNP-1 fraction in every experiment.
Research Areas Being Studied
Research areas discussed on this page reflect the Antimicrobial / Innate-Defense Peptides category and the sources cited below.
Findings Reported in Studies
Educational summary only — reported in cited studies, not a claim of proven benefit.
- Human neutrophil peptide 1-3, a component of the neutrophil extracellular trap, as a potential biomarker of lupus nephritis (2015):
- Altered serum levels of human neutrophil peptides (HNP) and human beta-defensin 2 (hBD2) in Wegener's granulomatosis (2011):
- Elevated levels of human beta-defensin 2 and human neutrophil peptides in systemic lupus erythematosus (2010):
- Defensins. Natural peptide antibiotics of human neutrophils (1985):
- Primary structures of three human neutrophil defensins (1985):
Study Tables by Evidence Type
Human Studies & Clinical Data
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| Human neutrophil peptide 1-3, a component of the neutrophil extracellular trap, as a potential biomarker of lupus nephritis | 2015 | 40 lupus nephritis patients, 40 SLE-without-kidney-injury, 63 IgA nephropathy, 20 minimal-change-disease, 33 healthy controls | Serum HNP1-3 levels were significantly higher in lupus nephritis patients than in other groups and healthy controls. | ||
| Altered serum levels of human neutrophil peptides (HNP) and human beta-defensin 2 (hBD2) in Wegener's granulomatosis | 2011 | 17 Wegener's granulomatosis (ANCA-associated vasculitis) patients, 24 matched healthy controls | Wegener's granulomatosis patients showed higher serum levels of hBD2 and pooled HNP than controls. | ||
| Elevated levels of human beta-defensin 2 and human neutrophil peptides in systemic lupus erythematosus | 2010 | systemic lupus erythematosus patients vs. controls | Elevated levels of hBD2 and pooled human neutrophil peptides (HNP) were observed in SLE patients. | ||
| Defensins. Natural peptide antibiotics of human neutrophils | 1985 | human neutrophils, biochemical/cellular study | Original identification of HNP-1, HNP-2, and HNP-3 as antimicrobial peptides localized to azurophilic granules of human neutrophils. | ||
| Primary structures of three human neutrophil defensins | 1985 | human neutrophil-derived peptides, structural/biochemical study | HNP-1, HNP-2, and HNP-3 share an identical 29-30-residue, three-disulfide-bond scaffold and differ from each other only by their N-terminal residue(s); HNP-2 lacks the extra N-terminal residue present in HNP-1 and HNP-3. |
Animal / Cell / Preclinical Data
No Animal / Cell / Preclinical Data Listed Yet
This section will be updated as sources are added.
Regulatory Documents & Official Trial Registries
No Regulatory Documents & Official Trial Registries Listed Yet
This section will be updated as sources are added.
Anecdotal Reported Patterns — Not Medical Advice
Anecdotal Reported Patterns — Not Medical Advice
Reported dosing patterns are included for educational context only. They are self-reported, unverified, not medical advice, and not instructions for human use. Community-submitted patterns are not yet available in this Phase 1 prototype; this section is a placeholder reserved for moderated, aggregated community data.
Lab Markers to Discuss With a Clinician
Educational topics only — not self-monitoring instructions.
FAQ
Disclaimer
Educational information only. This page summarizes published research on endogenous human alpha-defensin 1 (HNP-1) and does not constitute medical advice, a treatment recommendation, or dosing guidance for any related substance.
Educational use only. This content is provided for informational and research-summary purposes only. It is not medical advice, not a treatment recommendation, not a dosing guide, and not a substitute for care from a licensed medical professional. Nothing here is intended to diagnose, treat, cure, prevent, or mitigate disease. Reported dosing patterns, when shown elsewhere on the site, must be labeled either as Study / Trial Dosing or Anecdotal Reported Patterns — Not Medical Advice. Community reports are self-reported, unverified, and not scientific proof.
Community-reported experiences, once enabled, must be displayed only as moderated, anonymized, or aggregated data. They are anecdotal, self-reported, unverified, and should never be presented as proof of safety, efficacy, or expected results.
Content status: Published. Last updated 2026-08-29.
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