Age-associated decline in the in vitro development of cytotoxic lymphocytes in NZB mice.

The development of cytotoxic lymphocytes (CL) in in vitro mixed lymphocyte culture (MLC) was investigated in young (14 weeks), middle (40 weeks), and aged (80 weeks) NZB mice. Cytotoxic activity against H-2B alloantigens was measured by using the 51Cr release assay. The antigen dose to elicit the optimum development of CL in vitro was the same for all ages of NZB mice, but the level of the development of CL was consistently low and could be delayed by up to 24 hr in aged mice. This decline in the frequency of autoantibody against red blood cells nor to the decrease of the frequency of omega-positive cells in aged NZB mice. Aged (83 weeks) DBA/2 mice showed a similar decline in the development of CL. This decline of T cell function in aged NZB mice might be related to a physiologic aging process rather than to autoimmune disease.