AD is multifactorial, polygenetic skin disorder and is commonly viewed as immunologic in patho­genesis. Examination of skin biopsy samples from patients with AD has shown that S. aureus grows in colonies in the upper layers of the epidermis between keratinocyres. This suggests that an exponential increase in S. aureus could results from failure of the innate immune defense system. Naturally occurring AMPs are a critical component of this innate immune system. Among numerous AMPs, LL-37 and hBD-2 are the major classes of peptides in human skin. hBD-2 and LL-37 in human are normally produced by keratinocytes in response to inflammatory stimuli such as bacteria, viruses, and fungi. In fact, S. aureus can be isolated from skin lesions of most patients with AD. The mechanisms leading to increased S. aureus colonization in atopic dermatitis are unknown until now. A number of processes could contribute to increase in S. aureus colonization. These include disruption of skin barrier function from scratching, exposure of inflamed underlying skin from scrat­ching, loss of certain innate antibacterial activities from changes in lipid composition or hBD levels.

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1) TEWL measurement between involved and uninvolved skin

For comparisons of TEWL levels between involved and uninvolved sites in AD, measurements were performed 5 times for each site, repeatedly. The mean TEWL level of healthy donor was 7 g/hm2. The mean TEWL levels increased in both un­involved and involved sites than that of healthy donors, especially higher increased in involved sites

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Electrophoresis

The products were run on 1.5% agarose gel contain 1 yg ethidium bromide per millimeter. 20 yl of reaction mixture was mixed with loading buffer, separated by electrophoresis for 15 minutes at 100 voltages and visualized by UV transillumination.

Quantitative analysis

PCR products of hBD-2, LL-37 were normalized with GAPDH on DIG chemiluminescent film by using densitometer (volume of hBD-2/volume of GAPDH x 100, volume of LL-37/volume of GAPDH

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Subjects

Punch skin biopsies were taken from involved and adjacent uninvolved skin of 7 patients with AD after TEWL measuring. AD was diagnosed according to the standard criteria(Hanifin and Rjaka, 1982). Normal skin was obtained from healthy donor. Informed consent was obtained from all subjects after they were fully informed about the details and the potential risk of the study, and the study was ap­proved by the Ethical Committee of Chung-Ang University Hospital Institutes Review Board.

TEWL assessment

All subjects condition were first stabilized for 15 to 20 minutes in a climate and humidity-controlled room. Ambient temperatures ranged between 21° and 24° , with a mean relative humidity of 45%. TEWL was measured with a Tewameter TM 210 (Courage & Khazaka, Cologne, Germany) and estimated over representative involved skin sites as well as adjacent clinically normal appearing un­involved skin with AD. TEWL levels were also measured over normal skin of healthy donor.

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