Regulation of inhibitory and activating killer-cell Ig-like receptor expression occurs in T cells after termination of TCR rearrangements

A small fraction of T cells expresses killer-cell Ig-like receptors (KIR), a family of MHC class I-specific receptors that can modulate TCR-dependent activation of effector functions. Although KIR+ cells are enriched within Ag-experienced T cell subsets, the precise relationships between KIR+ and KIR- T cells and the stage of KIR induction on these lymphocytes remain unclear. In this study, we compared KIR- and KIR+ alpha beta T cell clones, sorted by means of the CD158b (KIR2DL2/KIR2DL/KIR2DS2) specific mAb GL183. We isolated several pairs of CD158b(+) and CD158b(-) alpha beta T cell clones sharing identical productive and nonproductive TCR transcripts. We showed that expression of functional KIR on T cells is regulated after termination of TCR rearrangements. Transcriptional regulation of KIR genes was documented in multiple T cell clones generated from the same donor, and the presence of KIR transcripts was also detected in KIR- T cells. These results document a complex regulation of KIR expression in T cells at both pre and posttranscriptional levels, under the control of yet undefined signals provided in vivo. The Journal of Immunology, 2001, 166: 2487-2494.