摘要
Natural killer （NK） cells are bone marrow derived, large granular lymphocytes, comprising approximately 10% to 20% of the mononuclear cell fraction in normal peripheral blood. They form a part of the first line defense mechanism against tumoural and viral spreading^1-4 Unlike T and B cells, NK cells do not require gene rearrangement for assembly of their receptor genes; rather, NK cells discriminate potential target cells based on the levels of self major histocompatibility complex （MHC） class I expression on such cells^5.6 There are two kinds of NK cell receptors^2.7.8 Inhibitory receptors recognize MHC class I molecules and deliver a downregulatory signal that inactivates the lytic machinery of NK cells. Stimulatory receptors expressed by NK cells deliver an activation signal.
Natural killer （NK） cells are bone marrow derived, large granular lymphocytes, comprising approximately 10% to 20% of the mononuclear cell fraction in normal peripheral blood. They form a part of the first line defense mechanism against tumoural and viral spreading^1-4 Unlike T and B cells, NK cells do not require gene rearrangement for assembly of their receptor genes; rather, NK cells discriminate potential target cells based on the levels of self major histocompatibility complex （MHC） class I expression on such cells^5.6 There are two kinds of NK cell receptors^2.7.8 Inhibitory receptors recognize MHC class I molecules and deliver a downregulatory signal that inactivates the lytic machinery of NK cells. Stimulatory receptors expressed by NK cells deliver an activation signal.
基金
This study was supported by the grants from the "973" Program about the Development of National Significant Elementary Research (No. 2006CB504206)
the Application Research Program of Prevention and Control of AIDS by Ministry of Health (NoWA2006-02)
the National Natural Science Foundation of China (No. 30400383).
