Age changes in immune response of rats to repeated injections of different doses of sheep's red cells

Abstract

The number of antibody-forming cells and the serum antibody titers were determined in adult and old rats after tenfold immunization with “small” (4·108 cells) and “large” (4·1010 cells) doses of sheep's red cells. The antibody (hemolysin and hemagglutinin) titers in the animals of both age groups were found to be either similar in magnitude or higher in the younger adult rats (for hemolysins, in the case of injection of the “large” dose of antigen). The number of direct plaque-forming cells in the spleen of the old animals was greater than in the young adults at all times of immunization, but the number of indirect plaque-forming cells was greater only at the end of immunization. The results are evidence of differences in maturation of the immune response in animals of different ages.