Qualitative changes in immunocompetent cells with age: reduced sensitivity to cortisone acetate.

Recent studies suggest that immunocompetent cells that respond to primary antigenic stimulus in old mice are different cell types from those that respond in young mice. This hypothesis was tested by determining the cortisone acetate sensitivity of antigen-sensitive lymphocytes from young and old donors. It was found that antigen-reactive lymph node lymphocytes from young donors are cortisone-acetate sensitive whereas the antigen-reactive lymph node lymphocytes from old donors are cortisone-acetate resistant.