Unresponsiveness of CD4⁺ T Cells from a Non‐Responder Strain to HgCl₂ is Not Due to CD8⁺‐Mediated Immunosuppression: an Analysis of the Very Early Activation Antigen CD69

Abstract

Injections of HgCl2 lead to autoimmune manifestations in genetically predisposed rats and mice. In this study, the authors examined the responsiveness of T subsets from different mouse strains to HgCl2 by tracing their expression of the very early activation antigen CD69. The authors found increased expression of the CD69 antigen on CD4+ T cells from the responder A.SW and BALB/c mice, but not on CD4+ T cells from the non-responder DBA/2 mice, indicating an activation of T helper cells in the responder strains. However, the CD69 antigen was induced on CD8+ T cells from all strains irrespective whether they were susceptible or resistant to mercury-induced autoimmunity. Since CD8+ T cells have been described as mediating immunosuppression and as being responsible for the resistance to autoimmune induction by mercury, the authors tested whether CD8+ T cells inhibited the activation of CD4+ T cells by HgCl2 in the non-responder strains. However, there was no evidence for a suppressive role of CD8+ T cells from the DBA/2 mice in the response to HgCl2. The findings indicate that T helper cells play a central role in the immunological effects of HgCl2 and unresponsiveness of T helper cells in the nonresponder strains is not due to CD8(+)-mediated immunosuppression.

HLA‐Association in Patients with Intolerance to Mercury and Other Metals in Dental Materials

“…Saito [11] found no significant HLA association for mercury and nickel sensitive patients, however DR4 was significantly increased in palladium sensitive patients. The possible involvement of HLA Class II antigens is indicated by data on the role of Class II molecules in experimental models for sensitivity to mercury chloride -HgCl 2 [1,6,9,10].…”

“…Expression of MHC Class I molecules in Brown-Norway rats is modified by HgCl 2 [10] and HgCl 2 induced systemic autoimmunity is due to direct effect of this metal compound on activation potentials of T and B cells [9]. Jiang and Möller [6] analysed the unresponsiveness to HgCl 2 of CD4 T cells in non-responder strains. Association of HLA-Class I and II with pe- riodontitis was recorded by Takashiba et al [16] and Terasaki et al [17].…”