Subchronic effects of pulp and paper mill effluents on the immunoglobulin synthesis of roach, Rutilus rutilus

Roach (Rutilus rutilus), from a unpolluted lake, were caged in a lake receiving treated waste waters from a pulp and paper mill 16 km upstream, and simultaneously a group of fish were held in cages in the unpolluted reference lake. The level of serum immunoglobulin of the fish kept in cages in these lakes was quantified. Serum immunoglobulin levels decreased when the fish were transferred to the contaminated lake and remained significantly reduced for the 8-week period fish were monitored. In another experiment fish were immunized with bovine gamma-globulin (BGG) after 5 weeks caging in the lakes. The kinetics of specific antibody synthesis were determined by assaying the number of antibody secreting cells in the spleen using enzyme-linked immunospot assay and by measuring the concentration of specific antibody in the serum. The peak response of the effluent exposed fish against BGG was lower than that for fish kept in the unpolluted reference lake, and the antibody titers, due to immunization, increased more slowly in the exposed fish. These results demonstrate that subchronic exposure of fish in a lake receiving treated waste waters from a bleached kraft mill affects the antibody-mediated immunity resulting in, besides lower levels of Ig, weak responsiveness against antigen.