Natural killer cells

Natural Killer CellsThe function of NK cells is to destroy irreversibly stressed and abnormal cells, such as virus-infected cells and tumor cells. NK cells make up approximately 5% to 10% of peripheral blood lymphocytes. They do not express TCRs or Ig.NK cells are endowed with the ability to kill a variety of virus-infected cells and tumor cells, without prior exposure to or activation by these microbes or tumors.Two cell surface molecules, CD16 and CD56, are commonly used to identify NK cells. CD16 is an Fc receptor for IgG, and it confers on NK cells the ability to lyse IgG-coated target cells. This phenomenon is known as antibody-dependent cell-mediated cytotoxicity (ADCC). The function of CD56 isnot known.Ref: Robbins and Cotran Pathologic Basis of Disease; 9th edition; Chapter 6; Diseases of the Immune System