Primary Study On The Tumor Evasion Mechanism By Receptors Of CD8~+ NKT Cell NKG2D/NKG2A And The Soluble Ligand MICA In The Patients With Lung Cancer

Objective: In the fight of resistance to tumor, cells immune plays a leading role. Natural killer T cells are new immune regulate cells of T lymphocytes. Ever research on the receptors NKG2D/NKG2A are only limited to T lymphocytes and NK cells. But recent researches display that receptors also exist on most NKT cells. The aim of the study is to investigate the levers of NKG2D/NKG2A expressing CD8~+NKT cells and sMICA in peripheral blood of lung cancer. To explore the relationship between those and clinical significance. To make relevant analysis of sMICA and NKG2D and discuss the immunosurveillance functions and mechanism of immune escaping of tumor in its happening and proceeding.Methods: Flow cytometry was used to determine the percentage of NKG2D/NKG2A expressing CD8~+NKT ,and ELISA was used to mesure the levels of sMICA in peripheral blood of 95 untreated lung cancer patients and 50 healthy controls.Results:(i)NKG2D was lower expressed on CD8~+NKT in lung cancer,the level of NKG2D in patients(77.07±5.77)% was lower significantly than that in the controls(84.13±4.49)%. In the TNM stage,the level of NKG2D in patients ofⅠ-ⅢA﹑ⅢB﹑IV stage were respectively (81.07±5.02)%﹑(76.95±4.70)%﹑(72.80±5.16)%,the level of NKG2D was significantly decreased in order(P<0.05).(ii)NKG2A was higher expressed on CD8~+NKT in lung cancer,the level of NKG2A in patients(33.58±8.82)% was higher significantly than that in the controls(25.31±8.38)%. In the TNM stage,the level of NKG2A in patients ofⅠ-ⅢA﹑ⅢB﹑ IV stage were respectively (25.10±6.93)%﹑(33.24±3.76)%﹑(43.64±6.10)%,the level of NKG2A was significantly increased in order(P<0.05).(iii)sMICA was higher expressed in the serum of lung cancer,the level of sMICA in patients (302.39±89.48)pg/mL was higher significantly than that in the controls(246.92±20.06)pg/mL. In the TNM stage,the level of NKG2A in patients ofⅠ-ⅢA﹑ⅢB﹑IV stage were respectively (265.64±75.32)pg/mL﹑(298.26±81.37)pg/mL﹑(350.48±98.24)pg/mL,the level of sMICA was significantly increased in order(P<0.05).( iv ) NKG2D-expressing CD8~+NKT had a perfect negative correlation with sMICA(r=-0.519,P<0.05) .Conclusion:(i)The lower lever of NKG2D-expressing and higher lever of NKG2A-expressing CD8~+NKT cells in lung cancer patients may be helpful in the evaluation of their happening and proceeding.(ii)sMICA is higher expression in the serum of lung cancer. It is relavant to TNM stage and may be helpful in the evaluation of diagnosis for lung cancer.(iii)NKG2D-expressing CD8~+NKT cells had a perfect negative correlation with sMICA. Accumulation of sMICA in serum may lead to the down-modulation of NKG2D-expressing CD8~+NKT which has been proposed to be a novel mechanism used by cancer cells to evade the tumor immunosurveillance .They may be potential indactors investigating immune functions.