Mononuclear cell-bound CD23 is elevated in both atopic dermatitis and psoriasis.

As patients with atopic dermatitis (AD) frequently have elevated serum IgE levels, the relation of this disease to CD23/Fc epsilon RII, a low affinity Fc receptor for IgE, and its soluble forms, sCD23, was studied. We examined the expression of CD23 on peripheral blood mononuclear cells (PBMC) as well as the serum IgE and sCD23 levels in 33 patients with AD and in 9 patients with psoriasis in comparison with 10 healthy donors. In AD patients, the numbers of CD23+ unfractionated PBMC and CD23+ small adherent cells were significantly elevated (P less than 0.05, resp. P less than 0.005). In psoriatic patients however, CD23 was also significantly elevated on PBMC (P less than 0.05) and on small adherent cells (P less than 0.05). There was no significant difference in the frequencies of CD23+ cells between AD and psoriasis patients. In all donors, CD23 could be detected only on B cells, but not on monocytes/macrophages. In AD patients who were examined twice, an increase or decrease of the clinical AD score was always accompanied by an increase or decrease, resp., of cell-bound CD23. The serum sCD23 level was not significantly increased in either group of patients. Our results suggest that CD23 should be considered as a nonspecific marker for B cell activation in the context of inflammation and not as a specific marker for AD.