Enhanced lymphocyte proliferative response to house dust mite in infants with atopic dermatitis

: Allergen-specific lymphocyte proliferation was measured in 24 children with atopic dermatitis and 20 non-atopic controls. The level of house dust mite-specific S.I.F. (stimulation index measured by flow cytometry) in the atopic children was significantly higher than that in the non-atopic controls in every age-group, suggesting that the elevation of the mite-specific S.I.F. level is related to the development of atopic dermatitis. The level of house dust mite-specific S.I.F. correlated significantly with the level of house dust mite-specific IgE-RAST in older children (r < 0.73, p < 0.001), indicating that S.I.F. reflects the activity of lymphocytes competent to promote the production of IgE. In the atopic infants, there was no significant positive correlation between the levels of mite-specific S.I.F. and mite-specific IgE-RAST since, although the former was usually elevated the latter was often very low or negative. The result suggests that the sensitization of T lymphocytes to house dust mite begins as early as in infancy prior to the development of mite-specific IgE antibody.