Activating CD94:NKG2C and inhibitory CD94:NKG2A receptors are expressed by distinct subsets of committed CD8+ TCR ?? lymphocytes

A subset of CD8(+) T cells express the natural killer cell receptors CD94:NKG2A or CD94:NKG2C. We found that although many CD8(+) T cells transcribe CD94 and NKG2C, expression of a functional CD94:NKG2C receptor is restricted to highly differentiated effector cells. CD94:NKG2A is expressed by a different subset consisting of CCR7(+) memory cells and CCR7(-) effector cells. Since NKG2A can only be induced on naive CD8(+) T cells while CD94(-) memory cells are refractory, it is likely that commitment to the CD94:NKG2A(+) subset occurs during the first encounter with antigen. CCR7(+)CD94:NKG2A(+) T cells recirculate through lymph nodes where upon activation, they produce large quantities of IFN-gamma. These cells occur as a separate CD94:NKG2A(+) T cell lineage with a distinct TCR repertoire that differs from that of the other CD8(+)CD94(-) T cells activated in situ.