The Expression Of NKG2D And Cytotoxicities Of NK Cells In Patients With Osteosarcoma

PART ONE THE EXPRESSION OF NKG2D IN NK CELLS IN PATIENTS WITH OSTEOSARCOMAObjective: This study is designed to explore the surface receptors NKG2D in NK cells in patients with osteosarcoma so as to understand the relationship between the surface receptors NKG2D on NK cell and the occurrence of osteosarcoma and to make a discussion on the clinical value of the detection in NKG2D.Methods: Expression of NKG2D was quantitatively analyzed by flow cytometry in the peripheral blood of 10 osteosarcoma patients and 10 health persons.Results: The expression of NKG2D were ( 95.10±2.97 ) % and (98.03±0.80)% respectively. The levels of NKG2D expression in NK cells of osteosarcoma patients were significantly lower than those in normal controls(P<0.05).Conclusions: Abnormal expression of NKG2D receptors in NK cells may be correlated with the occurrence and progression of osteosarcoma. PART TWO STUDY OF CYTOTOXICITIES OF NK CELLS IN PATIENTS WITH OSTEOSARCOMAImmune functions and the occurrence and expanding of tumor have many affinities. Natural killer (NK) cells represent a cell subset belonging to the innate immune system and have the ability both to lyse target cells and to provide an early arouse of immuno-regulatory cytokines. Unlike cytolytic T lymphocytes (CTLs), NK cells exert their cytolytic function swiftly at very early stage, without the need for previous in vitro or in vivo activation and are independent of a MHC restricted manner. They are thought to represent an important defense mechanism against various intracellular pathogens, such as viruses and tumors. NK cells are now a hotspot in immunological and oncological researches. On the other hand, to investigate the molecular immune-escape mechanisms of tumor must be of great importance in our research on looking for the essence of tumorigenesis and development and the ways to overcome the immune-escape phenomenon.Objective: To investigate the status of NK cells and effect of NKG2D polyclonal antibody(pAb) on cytotoxicities of NK cells so as to analyze the relationship between the cytotoxicities of NK cells and the levels of NKG2D and to understand the mechanism of occurrence of osteosarcoma.Methods: Peripheral blood mononuclear cells (PBMCs) were separated by centrifugation in 10 osteosarcoma patients and 10 health persons. The cytotoxicities of NK cells were analyzed by MTT colorimetry before and after NKG2D molecule on NK cells were blocked with NKG2DpAb.Results: It was found that in comparison with normal controls, the activity of NK cells were reduced obviously in patients with osteosarcoma; there was a close correlation between the cytotoxicities of NK cells and the levels of NKG2D.Conclusions: The cytotoxicities of NK cells in patients with osteosarcoma were reduced; the decrease of the NKG2D receptor is a reason for the descend of the activity of NK cells; the balance of NKG2D may play a role in the regulation of NK cell activity; the NKG2DpAb could inhibit significantly cytotoxicities of NK cells ; the immune-escape of osteosarcoma probably is relative to the down regulation of NKG2D.