The role of TCR stimulation and TGF‐β in controlling the expression of CD94/NKG2A receptors on CD8 T cells

Abstract

Following antigen recognition, murine CD8 T cells express CD94/NKG2A receptors. Our results show that this up‐regulation occurs rapidly in vitro and is accompanied by an ∼8‐fold increase in CD94 and ∼125‐fold increase in NKG2A mRNA. In contrast, only a twofold increase in NKG2C mRNA is noted. The addition of TGF‐β, but not IL‐10, IL‐12 or IL‐15, leads to a further increase in cell membrane expression of these receptors, as well as a ∼6‐fold increase in mRNA for both chains. TGF‐β also increases CD94/NKG2A expression on memory CD8 T cells that are re‐exposed to antigen. The effect of TGF‐β on increasing CD94/NKG2A expression on both naive and memory CD8 T cells occurs only when there is a concurrent stimulation through the TCR. In contrast, TGF‐β does not increase expression of CD94/NKG2A on resting or activated NK cells. We also show by using purified CD8 T cells, that TGF‐β acts directly on these cells. These results implicate a role for both antigen and TGF‐β in increasing expression of inhibitory CD94/NKG2A receptors on CD8 T cells.