In vitro effects of mercuric chloride (HgCl2) on human mononuclear cells

Due to the release of the toxic compounds of mercury from amalgam fillings, dental amalgam has been questioned as an adequate restoration material for tooth fillings. HgCl₂ has been found to be mitogenic for human blood lymphocytes in vitro. However, activation required much higher concentrations than are ever found in vivo. This study has been initiated to evaluate further the influence of HgCl₂ on human immunocompetent cells in vitro. It is found that HgCl₂ in a narrow concentration range has the ability to preferentially stimulate the CD4⁺ T cell subset to blast transformation and DNA synthesis. The reaction, when monitored during days 2–6, is maximal at day 6, and most blasts express the IL-2 receptor (IL-2R), indicating in vitro activation. The CD8⁺ T cell subset is not affected to the same extent. In addition, HgCl₂-induced lymphocyte reactivity is dependent on accessory cells, i.e. CD14⁺ cells.