Regulation of Adaptive Immunity by Cells of the Innate Immune System: Bone Marrow Natural Killer Cells Inhibit T Cell Proliferation

摘要

Natural killer (NK) cells represent the third largest population of lymphocytes after T and B cells and are derived from the same precursor cell, although they do not express antigen-specific receptors (Yokoyama et al., 2004). However, they can distinguish normal host cells from virus-infected or tumor cells and lyse the latter without prior immunological sensitization- hence the name "natural killer" cell (Trinchieri, 1989). It was determined that the NK cells recognize target cells because the latter are deficient in, or lack, the expression of host major histocompatibility (MHC) class I molecules (Karre et al., 1986).