[Per os desensitization in nickel contact eczema: a double-blind placebo-controlled clinico-biological study]

Ingestion of nickel (Ni) has been demonstrated to induce a specific state of tolerance in the guinea pig and mouse. In a pilot study conducted in 10 patients, we demonstrated that per os administration of Ni leads to reduced proliferation of specific lymphocytes and a lower number of responding lymphocytes in blood. The aim of this study was to evaluate the clinical and biological changes induced by the ingestion of Ni in a double-blinded placebo-controlled study.

Patients with nickel contact hypersensitivity were given a capsule of nickel sulfate containing 5 mg Ni (group A) or an identical placebo (group B) once a week for 7 weeks. Clinical criteria were assessed 49 days after study onset: objective measurement of lesion extent and intensity and quantitative patch tests at concentrations 2.4-0.8-0.2 and 0.05 p. 100. Likewise stimulation of specific lymphocyte proliferation and the number of circulating lymphocytes responding to Ni at limit dilutions were determined.

Thirty patients with nickel contact eczema were included in the study, 28 women and 2 men. There was no statistical difference between the two groups for the intensity of skin lesions or their clinical course, quantitative patch tests and lymphocyte stimulation tests. Conversely, the number of circulating lymphocytes responding to Ni was significantly lower in group A than in group B at study end (p < 0.05).

This double-blind placebo-controlled study confirmed that per os nickel can induce a significant reduction in the number of circulating lymphocytes responding to Ni. No other effect could be demonstrated for the clinical and biological parameters studied. These preliminary results should prompt a multicentric controlled trial including a larger number of patients with more severe lesions at inclusion and with a longer treatment duration.