Human beta defensin is absent in burn blister fluid

Defensins are a family of cationic antimicrobial peptides that participate in innate host defence. Human beta defensin-2 (HBD-2) is produced by human keratinocytes, and has a potent bactericidal activity against a wide spectrum of microorganisms. We have recently shown that expression of HBD-2 is present in normal skin and lost in the full-thickness burn wound. Defensins have been found in the blister fluid of chronic wounds. Our study was designed to examine blister fluid from partial-thickness burns for defensin content. Fluid from five patients was collected from partial-thickness burn blisters, and then analysed by sandwich Enzyme-Linked Immunosorbent Assay (ELISA) with a monoclonal antibody and rabbit polyclonal antibody to HBD-2. The assay was validated against a Western blot assay for HBD-2 in samples of bronchoalveolar lavage fluid from patients with inflammatory lung disease. No HBD-2 was detectable in any of the burn blister fluids analysed. HBD-2 is lost in the full-thickness burn wound, and we have now demonstrated its absence in burn blister fluid. This finding represents evidence of a host defence defect within the burn wound and suggests a possible therapeutic role for antimicrobial peptides in the management of burn wounds.