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Effect of age on the induction of autoantibodies.

Three experimental models were used to compare the ease of inducing autoantibodies in young and old mice. Autoantibody to thyroglobulin (Tg) induced by immunization with cross-reactive xenogeneic Tg in Freund's complete adjuvant and autoerythrocyte antibody induced by the injection of xenogeneic erythrocytes were studied in C57Bl/6 and BALB/c male mice. In both strains, the anti-thyroglobulin antibody response to lower doses of xenogeneic Tg was significantly lower in old as compared with young animals. There were no detectable differences in incidence or strength of the direct Coombs' test following the administration of rat erythrocytes to old or young animals. In contrast, anti-mouse erythrocyte autoantibody-secreting spleen cells, generated in culture and assayed on bromelin-treated mouse erythrocytes, were more numerous in cultures of spleen cells from old as compared with young mice. These results suggest that the regulation of the autoantibody production which is stimulated by cross-reactive antigens is under different control from the spontaneous age-related increase in autoantibodies.