a limiting dilution system has been applied to compare precursor frequencies of proliferating t lymphocytes ( ptl-p ) , of t-cell growth factor-secreting t cells ( ttcgf-p ) , and of cytotoxic t cells ( ctl-p ) in lymphocyte populations of aged , mrl/mp-lpr/lpr ( mrl-lpr ) mice and the congeneic strain mrl/mp- +/+ ( mrl-n , ) , or the h-2k-compatible strains akr/n and b10.br responding to the mitogen concanavalin ( cona ) , to alloantigens ( h-2 ) or to trinitrophenol ( tnp ) -modified syngeneic cells .
C1327616
secreting
C0007634
cells