Humoral immune responses characteristic of testosterone-propionate-treated chickens

White Leghorn chickens treated with testosterone-propionate on the 3rd day of embryonation were immunized with a mixture of sheep red blood cells, Brucella abortus and Salmonella pullorum at various ages, and the resulting agglutinins were titrated. The production of IgM antibody against sheep red blood cells was not affected significantly by testosterone-propionate. On the contrary, immune responses against the bacterial antigens were strongly suppressed by the same treatment. Production of IgG antibodies was strongly suppressed by the same treatment. There was little correlation between the production of IgM antibody against sheep red blood cells and the presence of bursal follicles. Immune responses against bacterial antigens correlated with the presence of the follicles. Production of IgG antibodies also correlated with the maintenance of bursal lymphoid structure.