There is an induction of anti-DNA antibodies in mice following the administration of bacterial lipopolysaccharides, Dextran sulfate and PPD, which is closely associated with the property of these substances to trigger a polyclonal B cell activation. In the experiments model of African trypanosomiasis there is also an intense polyclonal antibody synthesis paralleled by the formation of several autoantibodies: anti-DNA, anti-bromelain treated mouse red blood cells and antithymocyte antibodies.