The suppressive effect of continuous infusion of bilirubin on the immune response in mice

Mice (strains Balb/c and A/J) received an intravenous infusion of bilirubin for a 1 d period. The infusion was delivered at various phases of the primary reaction; the degree of the immune response was expressed as the number of antibody-forming cells against sheep erythrocytes. Bilirubin infusion during both the inductive and productive phase of the primary reaction decreased significantly the immune response. We assume that bilirubin influences the differentiation of immunocompetent cells immediately after their contact with the antigen; in addition it acts in the period of the quantitative increase of the number of antibody-producing cells.