Beta-Defensin 2: How an Antimicrobial Peptide Links Skin Infections to Allergic Diseases

HBD2 promotes mast cell activation and degranulation, linking antimicrobial defense to allergic reactions. Elevated serum HBD2 found in atopic dermatitis, psoriasis, and chronic spontaneous urticaria. CSU patients with angioedema have higher HBD2 than those without. HBD2 is produced by keratinocytes, epithelial cells, and macrophages in response to microorganisms or pro-inflammatory cytokines.

Narrative review of published literature on human β-defensin 2 in dermatological and allergic conditions, covering its production, antimicrobial functions, role in mast cell activation, and clinical associations with skin diseases.

Understanding how antimicrobial peptides like HBD2 trigger allergic responses explains why skin infections often worsen allergic diseases. This dual-function concept could lead to new therapeutic strategies — either dampening HBD2's allergic effects while preserving antimicrobial function, or using HBD2 levels as a biomarker to guide treatment decisions in skin diseases.

The relationship between infections and allergies has puzzled immunologists for decades. HBD2 provides a molecular link — the same peptide that fights infection can also activate allergic pathways. This has implications beyond skin disease, potentially explaining why infections trigger or exacerbate allergic conditions throughout the body.

Narrative review without systematic methodology. Limited data on HBD2 skin expression levels in allergic diseases (most studies measure serum levels). The causal relationship between elevated HBD2 and allergic disease is not established — HBD2 elevation could be a consequence rather than a cause. Published in a regional dermatology journal with potentially limited peer review scope.