Rare Lineage

Abstract

A small subset of T lymphocytes express markers characteristic of natural killer (NK) cells and has been shown to regulate adaptive immune responses. Compared with conventional T cells, the development of these NKT cells is poorly understood, although it is known that they are positively selected by major histocompatibility complex-like CD1 ligands within in the thymus. Benlagha et al. (see the Perspective by MacDonald) used tetramer staining to characterize NKT cells precursors in wild-type populations of thymocytes and to track their emigration from the thymus into peripheral tissues. The NK phenotype displayed by these cells actually occurred after these cells exited the thymus. More striking was a progression from expression of the cytokine interleukin-4 to interferon-γ, which may reflect distinct mechanisms of immune regulation mediated by these cells. K. Benlagha, T. Kyin, A. Beavis, L. Teyton, A. Bendelac, A thymic precursor to the NKT cell lineage. Science 296, 553-555 (2002). [Abstract] [Full Text] H. R. MacDonald, T before NK. Science 296, 481 (2002). [Summary] [Full Text]