Clinical, Epidemiological, Laboratory and Therapeutic Investigation

BACKGROUND: The diagnosis of nickel sensitivity is made by epicutaneous patch testing. OBJECTIVE: To develop a more sensitive and specific test. PATIENTS AND METHODS: Nineteen patients with positive patch test reactions to nickel and 25 controls were submitted to lymphocyte proliferation test. Mononuclear cells were isolated from peripheral venous blood and cultivated in triplicate in culture plates (2x10 5 cells/well) with: culture medium only, nickel sulfate (156.25; 78.13; 19.53; 9.77 and 2.44µM) and optimal concentrations of Candida albicans antigen as well as pokeweed, phytohemagglutinin A and anti-CD3 antibody (OKT3) mitogens. Tritiated thymidine was added to plates, radioactivity incorporated by cells was measured and the results expressed by the stimulation index (SI). R ESULTS: The lymphocyte proliferative response was higher in cases than in controls in all nickel concentra- tions tested. Considering positive test reactions when SI > 3, none of the controls and 16 (84.21%) cases were positive in at least one of five concentrations used. The proliferative responses to Candida albicans and mitogens were similar in cases and controls, demonstrating normal cellular immunity in both groups. CONCLUSION: The lymphocyte proliferation test is useful in diagnosis of nickel sensitivity.