Dithiols as chelators : A cause of bullous skin reactions

Chelation therapy with (RS)-2,3-Bis(sulfonyl)propane-1-sulfonic acid (DMPS) after an occupational lead exposure led to the development of a severe bullous drug eruption. Skin tests and histology/immunohistology of the test reactions indicated a T-cell-mediated immune response against DMPS. Metal-binding thiol groups as in DMPS are chemically highly reactive and therefore effectively mediate the development of immunogenic hapten (DMPS)-protein complexes. Therefore, the pharmacological effects and sensitization potential of dithiols are tightly connected. Cross-reactivity of DMPS to other chelators like D-penicillamine is possible; the indications for chelation therapy should be weighed carefully.