Defective T cell function in atopic dermatitis.

The cellular immune system of 37 patients with atopic dermatitis (AD) was assessed by measuring peripheral blood T and B cells and the in vitro lymphocyte response to graded doses of phytohemagglutinin (PHA) (background and 6 concentrations of PHA from 100 to 1.6 mug). These were then correlated with clinical severity, ecosinophil counts, and serum IgE levels. The IgE levels (1,482 IU +/- 252 SEM), eosinophil counts (977 +/- 143), and absolute number of B cells (958 +/- 123) were significantly (p less than 0.05) higher than in age-matched controls (70 IU +/- 28, 182 +/- 79, and 480 +/- 60, respectively), and each significantly (p less than 0.05) correlated with the clinical severity. By contrast, percent B lymphocytes (20 +/- 1), percent (51 +/- 2) and total (2,357 +/- 217) T cells did not differ from controls. Eleven patients had low percent T cells (less than 40%); clinical and laboratory evaluation in these patients did not differ from the remaining 26. Lymphocytes from AD patients had higher background deoxyribonucleic acid (DNA) synthesis than controls (suggestive of increased number of B cells) and significantly depressed responses at the low PHA concentrations (6.3, 3.1, and 1.6 mug), which significantly correlated (p less than 0.05) inversely with IgE levels. These studies suggest a subtle defect in T lymphocyte function leading to increased B cells and increased IgE production.