The Effects Of X-ray Irradiation On Lymphocyte Proliferation And NK Cell Activity In Cord Blood

PrefaceThe immaturity of cord blood cell can inhibit the GVL response and cause CBT relapse . DLI can decrease tumor relapse rate, but it increases the GVHDrate. And mixed cord blood transplantation may also cause high GVHD rate. This study investigated the effects of x - ray irradiation in different dose on lymphocyte proliferation and NK cell activity in cord blood to find the clinical value of x - ray irradiation on CBT.MaterialsK 562 cells Liaoning Tumor Institute3H - TDK China Nulear InstituteCon A America Sigma Corp.Cord blood China Medical 2nd HospitalAirforce 463 HospitalVarian 6 MV x-ray Liaoning Tumor Hospital Methods(1 )ord blood was got from 37 -42 week newborns. In 6 hours monocytes were isolated and cultured in RPMI 1640 (hyclone) which contented 10% cow fetus serum.The lymphocyte proliferation measurementIsolated monocytes in concentration 1 106/ml proliferated by Con A administration and were cultured under 37 ,5% CO2 and saturated humidity condition for 24 hours. Then they received x - ray irradiation in different dose (0. 25Gy,0. 5 Gy,l Gy, 2Gy,4 Gy, 6Gy, 8Gy and 16 Gy). After another 56 hours culturation, 3H - TDR was administrated 8 hours later, the cell number was measured. Lymphocyte proliferation response was evaluated by SI. And it was significant when SI was no less than.(2)NK cell actioity measurementWith 48 hours culturation and activity more than 98% K 562 cells were set in concentration 1 106 /ml. After administrated of H -TDR they were cultured under the same condition as monocytes for 6 hours. Then the concentration was set in 5 10 /ml . Cord blood monocytes in concentration 1 107 /ml were irradiated in different dose x - ray like above. The two kinds of cells were put together and cultured under the same condition for 18 hours then measured.ResultsThe effects of x - ray irradiation on Cord blood cymphocyte.0.25 - 16 Gy x - ray irradiation inhibited lymphocyte proliferation significantly. The inhibition role was correlated with irradiation dose positively ( r = 0. 839, P < 0. 05 ). Lymphocyte proliferation was not found in range of 4Gy - 16Gy.The effects of x - ray irradiation on cord blood NK Cells.Irradiation dose from 0.25 Gy to 2Gy could enhance NK cells activity. Irradiated in 4Gy x-ray, the activity of NK cells was reservedand In range of 6Gy -16Gy,it was inhibited significantly.DiscussionTo enhance the GVL response and inhibit the relapse is an important goal in current CBT study. And how to control the GVHD is also a problem to be resolved. Zhang Li Cheng et al found that 7. 5Gy X - ray could inhibit the GVHD and reserve its anti - leucemia action, waller et al reported that when dorvor leucocytes irradiatd by 7. 5Gy X - ray were transfused to BMT recurrent patients, the therapy effect was obvious.This study indicated that 4Gy X - ray irradiation could inhibit the lymphocyte prolifeation completely and reserved the NK cells anti -tumor activity at the same time . So in donor lymphocyte transfusion or mixed CBT 4Gy X - ray irradiation on cord blood cell may decrease GVHD rate and reserved GVL response at the same time.Conclusion The ability of lymphocyte proliferation was inhibited and the activity of NK cell was reserved when irradiated with the dose of 4Gy X - ray. So if the lymphocytes were irradiated with the dose of 4Gy X - ray before donor lymphocytes infusion, mix - cord blood transplantation,the effect of graft versus host disease( GVHD) would be decreased and the effect of graft versus leukemia (GVL) would be reserved simultaneously in adoptive cellular immunotherapy.