A Study On Partial Pathogenesis Of Staphylococcal Superantigens In Atopic Dermatitis

ObjectivesTo determine the production of staphylococcal superantigens (SAgs) by skin-colonizing Staphylococcus aureus (S.aureus) in patients with atopic dermatitis (AD) and eczema(EC). To determine the correlation among SAgs production by skin lesion-colonizing S.aureus, clinical severity , serum level of IgE,IL-4 and IFN-y in patients with AD and EC. To determine the potential induction of corticosteroid resistance in human PBMCs by staphylococcal superantigen Methods1. SAgs production by 140 S.aureus strains from skin in 117 atopic dermatitis and 199 eczema patients was investigated with reverse passive latex agglutination assay.2. One hundred and twenty three S.aureus strains were isolated from skin lesions in 91 AD and 174 EC patients.Correlations of SAgs production with eczema area and severity index(EASI), scores of six kinds of lesions and some serologic changes were analyzed.3. The capacity of dexamethasone to inhibit proliferation of PBMCs from healthy subject with staphylococcal enterotoxin B(SEB) ,versus PHA, was tested by MTT assay.The secretion levels of IFN-γ and IL-4 ofserum collected from PBMCs cultures were detected with Human Cytokine Sandwich ELISA Kits. Results1. Among 140 S.aureus strains,60 strains produced SAgs with positive rate of 42.9% , 43 strains produced only one kind of SAg and 17 strains produced at least two kinds of SAgs. 51.5% strains from atopic dermatitis patients produced SAgs and there was no statistically significant difference in producing SAgs between lesional and non-lesional strains in atopic dermatitis. 34.7% strains from eczema patients produced SAgs and they were all lesional strains.The total SAgs, lesional SAgs and toxic shock syndrome toxin- 1(TSST-1) productions were all higher in strains from atopic dermatitis than those from eczema. The lesional SAgs and TSST-1 positive rates were higher in strains from AD than those from EC.2. AD patients with SEB-secreting S. aureus had a higher EASI than those without SEB-secreting S. aureus and without skin-colonizing S. aureus. In EC patients, the severity of the disease was not associated with SAgs production ,but SAg-producing patients had a higher fissure scores.The serum levels of total IgE, IL-4 and IFN-γ of AD and EC patients were not correlated with SAgs, but the total IgE level of EC patients colonized with SAg-secreting S. aureus was higher than those without S. aureus colonized.