Compared with the healthy control group , AS patients had significantly lower BTLA expression in CD3 ( + ) T cells and CD4 ( + ) T cells from the peripheral blood ( P < 0.01 or P < 0.05 ) , the decreased levels of SOD , CAT and TAOC , and significantly increased ROS , RNS and MDA values ( P < 0.01 or P < 0.05 ) .