Immunological studies on the peripheral blood mononuclear cells in metal allergy patients

Recently, the number of patients with dental metal allergy has risen significantly. The aim of this study was to evaluate the clinical availability of the lymphocyte stimulation test (LST) using metal reagents as a method for diagnosing metal allergy. In vitro, peripheral blood mononuclear cells (PBMC) from 18 patients with metal allergy and five healthy volunteers were examined by LST using 12 metal reagents (HAuCl4, PdCl2, NiSO4, CoCl2, CuSO4, SnCl4, K2Cr2O7, MoCl5, H2PtCl6, IrCl4, AgBr, FeCl3). To define metal allergy, a patch test (PT) was performed with metal reagents, and then the components of dental alloys in their mouth were analyzed. The expressions of CD 4, CD 8, CD 25, and CLA of metal-specific T cells were determined by flow cytometric analysis (FACS). PBMC from patients with positive PT showed LST positive for nickel sulfate (Ni), gold chloride (Au), palladium chloride (Pd) and cobalt chloride (Co). The results of LST in other metals indicated negative in spite of the positive result by PT. FACS results indicated the increase of CD 4 + T/CD 8 + alpha 4 + T cells, CD 4 + T/CD 8 + CLA+ T cells by stimulation with metal reagent. Thus, metal-specific T cells were stimulated in PT positive patients, so LST could be a more specific test for diagnosing dental metal allergy.