Lymphocyte Transformation in Nickel Allergy: Amplification of T‐lymphocyte Responses to Nickel Sulphate by Macrophages in Vitro

The cell-mediated immunity of thirty-four nickel contact dermatitis patients was evaluated by performing lymphocyte stimulations with NiSO4 (1.25 and 6.25 microgram/ml) and tuberculin (PPD), phytohaemagglutinin-P, pokeweed mitogen, and concanavalin A. Twenty-six of the patients were nonatopic and eight atopic. Forty-nine healthy subjects served as controls. Nickel sulphate stimulation was significantly increased (P < 0.005) in the allergic subjects, whereas PPD stimulation was decreased (P = 0.01). The responses to the other mitogens did not differ significantly between the control subjects and the patients. The lymphocyte transformation reaction to nickel sulphate was shown to occur in T cells and to be enhanced by the helper function of macrophages.