[NK cells: new insights on physiology and clinical implication in diseases].

INTRODUCTION: Natural killer cells are cytotoxic lymphocytes of innate immunity. These last ten years our knowledge about the mechanisms that regulates NK cell function has greatly improved. Our purpose is to present a review of these new acquisitions and their potential implications in human disease. CURRENT KNOWLEDGE AND KEY POINTS: NK cell function is regulated by a repertoire of NK cell receptors and is diversified by recognition of MHC class I by a multigenic and multi-allelic family of NK receptors. Analysis of NK cell repertoire has been used to investigate features that characterize NK cells in pathological situations. Apart from their direct cytotoxic potential to eliminate target cells, recently identification of mechanisms that control NK cell mediated cytokine production and cross talk with dendritic cells emphasize the role of NK cells in the regulation of acquired immune response. FUTURE PROSPECTS AND PROJECTS: These findings have lead to a better knowledge of the importance of the NK cells in several human diseases. It has been shown that NK cells are actors of the immunosurveillance of tumoral and infectious challenges. Allo or auto reactivity of the NK cell compartment have also been suggested in autoimmune diseases, infertility or foetal loss and transplantation. Ongoing research on NK cells in the fields of human diseases is increasing and will clarify the utility of the evaluation of the NK cell compartment and their receptors in clinical practice.