CD27 and rheumatoid arthritis: Seven major CD8 T cell populations were examined by using the combination of CD45RA, CD27, CCR7, and CD28 cell surface markers to define naïve (CD45RA+CD27+CCR7+CD28+), TEMRA (CD45RA+CD27-CCR7-CD28-), early-like effector memory (CD45RA-CD27-CCR7-CD28+), effector RA- [CD45RA-CD27-CCR7-CD28- (TE RA-)], early memory [CD45RA-CD27+CCR7-CD28+ (early)], intermediate memory [CD45RA-CD27+CCR7-CD28- (intermediate)], and central memory [CD45RA-CD27+CCR7+CD28+ (CM)] (Figure 2A) CD8 T cells [as described in a consensus paper (21)].