Strain differences in the effect of mercury on murine cell-mediated immune reactions

The effect of mercuric chloride on mitogen-induced DNA synthesis was investigated using lymphocytes from SJL and DBA mice, which are known to be susceptible and resistant to induction of autoimmunity by mercury, respectively. Treatment of SJL mice with 5 ppm mercuric chloride in their drinking-water for 2 wk resulted in a two- to three-fold increase of concanavalin A and lipopolysaccharide-induced thymidine incorporation in splenocytes. Mitogen-induced thymidine incorporation in splenocytes from identically treated DBA mice was not significantly different from that seen in controls. In vitro treatment of splenocytes from SJL mice with mercury caused a dose-dependent increase of concanavalin A-, lipopolysaccharide and phytohaemagglutinin-induced thymidine incorporation. This effect was optimal when 10(-7)-10(-8) M-mercuric chloride were added as a pulse 1 hr before the addition of mitogens, whereas higher and lower concentrations were less effective. The mitogen-induced DNA synthesis in splenocytes from DBA mice was either not affected by the addition of mercuric chloride or decreased by higher mercury concentrations. The addition of mercury to thymocytes from DBA and SJL mice caused a slight and moderate increase, respectively, in concanavalin A-induced thymidine incorporation.