Investigation of the association between mercury sensitization and HLA-DR6.

HLA molecules, polymorphic membrane glycoproteins, are classified into 2 groups: those expressed on the surface of almost all nucleated cells (HLA class I molecules), and those found on the surface of cells mainly involved in the immune response (HLA, class H molecules) (1). In guinea pigs and mice, the genes that control delayed hypersensitivity reactions have been shown to be linked with those of the major histocompatibility antigens (2). The immune response genes (Ia) of mice have their homologues in the human HLA-DR locus. Although significant increases in HLA-DRw6 antigen in nickel-contact-sensitive patients have been reported (3), other attempts to investigate the link between HLA typing and metal contact sensitivity have resulted in conflicting results for nickel, cobalt and chromium (I). However, there have been no reports of previous investigations of the association between mercury sensitization and HLA-DR. Previously (4), we investigated various factors related to mercury sensitization of 156, 4th year medical students between 1993 and 1994. We found that mercurysensitized students had a significantly higher frequency of eczema caused by cosmetics, shampoos, soaps and hair creams, and had significantly more teeth modified with metals compared to controls. In addition, their urinary mercury concentrations were significantly higher than those of the non-sensitized group. However, mercury sensitization was not significantly associated with