B lymphocytes in contact dermatitis.

The expression of immunoglobulin on the membrane of peripheral blood lymphocytes of patients with contact dermatitis has been investigated using a sensitive rosette technique. The proportion of such cells in these patients is increased compared to normal values. However, the absolute values obtained are very much lower than has been reported from previous studies. The re-evaluation of immunoglobulin expression is discussed against a background of improved methodology and the established finding that individual lymphocytes may express more than one isotype.