Patients with atopic dermatitis — also known as eczema — are susceptible to skin infections, and there are increasing concerns that they can develop severe infections following smallpox vaccination. In October 10 New England Journal of Medicine, Peck Ong and colleagues at the National Jewish Medical and Research Center, Denver, USA, show that a deficiency in the expression of antimicrobial peptides may account for the susceptibility of patients with atopic dermatitis to skin infection with Staphylococcus aureus (New England Journal of Medicine, 347:1151-1160, October 10, 2002).

Ong et al. measured the expression of LL-37 and HBD-2 protein (two peptides with antimicrobial activity against S. aureus) in skin-biopsy specimens from patients with psoriasis (an inflammatory disorder), patients with atopic dermatitis, and normal subjects. They observed the presence of abundant LL-37 and HBD-2 in the superficial epidermis of all patients with psoriasis but significantly decreased levels in lesions from patients with atopic dermatitis. In addition, real-time RT-PCR showed significantly lower expression of HBD-2 mRNA and LL-37 mRNA in atopic lesions compared to that seen in psoriatic lesions.

"These findings point to the role of antimicrobial-peptide function in clinical disease and highlight the importance of considering the interaction between the innate and adaptive immune systems," conclude the authors.