Expression of CD45-Restricted Form B in (NZW × BXSB) F1 and MRL/Mp-1pr/1pr Mice

Expression of CD45RB on CD4(+) or CD8(+) cells in combination with TCRV beta usages (V beta 6, V beta 8.1, V beta 8.2, V beta 11 and V beta 17a) in normal mouse strains (BALB/c and C57BL/6) was compared with autoimmune-prone strains ((NZW x BXSB) F1 and MRL/lpr) at young and old ages, The frequencies, and also the numbers of CD45RB cells in CD4(+) T cells with various TcR repertoires was significantly less in the autoimmune-prone strains at old ages, while, in normal control strains, they remained unchanged. Furthermore, CD4(+)/CD45RB(-) cells are CD44(high) and CD62L (L-selectin).(low) These findings suggest that most T cells, especially CD4(+) T cells, in old W/BF1 and old MRL/1pr mice, were activated and this may reflect the elevation of autoantibodies and the progress of autoimmune status in aged autoimmune-prone mice, This will be discussed in relation to the progress of the autoimmune diseases.