B lymphocytes, T lymphocytes and phytohaemagglutinin responsiveness in atopic dermatitis.

The spontaneous binding of sheep erythrocytes to human lymphocytes with the formation of rosettes was used as a measure of thymus-derived lymphocytes and the rosette formation with complement-coated sheep erythrocytes as a measure of bursa-dependent lymphocytes in the peripheral blood of patients with atopic dermatitis. Both percentage proportion and the absolute number of thymus-derived lymphocytes were slightly but significantly reduced. In a few patients with atopic dermatitis the percentage and absolute number of bursa-dependent lymphocytes were increased. However, when all values were considered, no significant differences were demonstrated. The responsiveness of cultured lymphocytes to phytohaemagglutinin was normal when the culture medium contained foetal calf serum. The response of normal lymphocytes was not impaired by serum from patients with atopic dermatitis. However, the response was depressed when atopic dermatitis lymphocytes were cultured in medium containing autologous serum, indication that a partial lymphocyte defect becomes manifest only in the presence of a serum factor, presumably IgE.