Serum immunoglobulin levels in monkeys treated with methylmercury

Observations on patients with Minamata disease and studies in mice and rabbits have demonstrated that MeHg decreases synthesis of antibodies toward pathogenetic and non-pathogenetic antigens. Our study was intended to verify this hypothesis by using monkeys as test animals. Four groups of Cynomologus monkeys were treated for 120 days with: 0, 0.4, 4.0 and 50 micrograms/kg b.w./day of MeHg. Every 15 days each monkey was examined and given a blood test to evaluate immunoglobulins G, M, A (IgG, IgM, IgA). A dose-dependent transient reduction of gamma globulin was observed in all test groups as compared to the control. This effect was clearly evident after 30 days of treatment and disappeared after 60 days. At the highest dose the immunoglobulin G was significantly decreased as compared to the control after 45 and 60 days of treatment. After 120 days, all the exposed groups showed significantly lower levels of immunoglobulin G. Immunoglobulin M was significantly lower in the groups given 4.0 and 50 micrograms/kg b.w./day compared to the control, after 45, 60 and 120 days.