Proliferation of nickel-sensitive human lymphocytes by corrosion products of orthodontic appliances.

Lymphocyte transformation tests were performed on peripheral blood taken from individuals with a history of contact dermatitis who also presented with a positive patch test to nickel sulphate, and from individuals with no history of contact dermatitis. The results implied that nickel leached out from metallic orthodontic appliances in sufficient amounts and of a chemical nature adequate to stimulate proliferation of lymphocytes from some of the nickel-sensitive subjects.