Gold compounds clinically used as immunomodulators have high potential to evoke hypersensitivity reactions as an adverse effect. To explore the mechanism of gold allergy, we immunologically characterized T cells infiltrating skin rashes and generated 44 gold-specific T cell clones and lines from a rheumatoid arthritis patient who developed skin rashes and systemic symptoms after gold treatment. CD4(+) and CD8(+) cells predominantly infiltrating the skin rashes and some of the T cell clones and lines shared common Vbetas. These cells exhibited Th0-like, Th2-like, and Tc1-like cytokine profiles, and showed chemotactic activities for thymus and activation-regulated chemokine and IFN-gamma-inducible protein-10 corresponding to the cytokine profiles. T cell recognition of gold consisted of MHC-restricted and MHC-independent pathways. Blocking studies with anti-MHC Abs indicated that the groove of MHC in APCs, where Ags should ordinarily be settled, did not serve as a conjugating site of gold for these T cells in certain cases. These observations raise the possibility that gold-specific CD4(+) and CD8(+) T cells and APCs promiscuously interact under stimulation with gold, resulting in various clinical manifestations in gold allergy.