Accessory molecules and antigen requirements for young and aging cytotoxic lymphocytes

In this study I have investigated whether young and aging alloreactive cytotoxic T-lymphocytes (CTL) have comparable antigen requirements, and whether the accessory molecules Ly2 and LFA-1 participate similarly in cytolysis mediated by young and old cells. Spleen and lymph node cells from young and aging, naive and primed mice were stimulated in bulk culture with allogeneic cells; cytotoxicity and proliferation were then measured. Additionally, lymph node cells were cultured under limiting dilution conditions, and the resultant clones here tested for cytotoxicity in the presence or absence of antibodies against Ly2 and LFA-1. I found that accessory molecules from naive and primed, young and aging splenic CTL participated similarly in cytolysis. However, both cytotoxic and proliferating splenic T-cells from aging mice required a greater alloantigen concentration for optimal response. Heterogeneous lymph node CTL from old mice demonstrated less cytotoxicity than young CTL, and, on the clonal level, old naive CTL clones were less active than young clones. Naive aging clones were more resistant than young clones to anti-Ly2 and anti-LFA-1. After priming, clone activity among the various age groups did not differ. These results suggest a qualitative difference between young and old cytolytic cells prior to alloantigen priming in vivo.