The immune response in aged C57BL/6 mice. II. Characterization and reversal of a defect in the ability of aged spleen cells to respond to the adjuvant properties of Fc fragments.

Fc fragments derived from papain cleavage of human Ig were found to be unable to enhance the in vitro anti-SRBC response of aged mice. The inability of aged spleen cells to respond to the adjuvant properties of Fc fragments is localized to the aged T cell population. The addition of Fc fragments to cultures of aged B cells and young adult T cells, but not young adult B cells and aged T cells, resulted in an enhanced anti-SRBC response. The Fc fragment adjuvant defect in spleen cells from aged mice can be reversed by the addition of IL 2 to culture. The addition of either Fc fragments alone or IL 2 alone with antigen to intact aged spleen cell populations did not result in an enhanced anti-SRBC response. When aged spleen cell cultures receive both Fc and IL 2, however, a marked enhancement is observed. These data indicate that IL 2 action on aged spleen cells results in the acquisition of reactivity to Fc adjuvant action by aged mice.