[Enhanced lymphocyte proliferative response to house dust mite in the older but not in the younger asthmatic children].

Allergen-specific lymphocyte proliferation was measured by flow cytometry in 16 children with atopic dermatitis (AD). 26 with bronchial asthma (BA) and 13 non-atopic controls. Although the level of mite-S.I.F. (stimulation index measured by flow cytometry) in the younger AD children (2-7 y) was significantly higher than that in the non-atopic subjects (189.6 +/- 70.7 vs 113.9 +/- 11.0, p < 0.02), there was no elevation in the younger BA children (122.6 +/- 23.4). It is therefore likely that the elevated mite-S.I.F. level is related to the development of the allergic cellular inflammation representing the pathology of AD, rather than the IgE-mediated allergic reaction as a mechanism of childhood BA. Because the level of mite-specific IgE antibody in the younger BA children is elevated (93.6 +/- 41.2 PRU/ml), the result also indicates that mite-specific peripheral T lymphocytes do not play a critical role in stimulating the mite-specific IgE synthesis. On the contrary, the older BA children (8-15 y) showed an elevated mite-S.I.F. level (176.0 +/- 54.6) significantly higher than that in the non-atopic subjects (114.6 +/- 13.9, p < 0.05) as well as that in the younger BA children (p < 0.05). Because other investigators have reported that the level of mite-specific lymphocyte proliferation is increased in the adult BA patients, the transition from childhood BA to adult-type BA may start at the age of about 8 y.