The aim of the present study was to investigate whether low-dose priming radiation induces antitumor immunity that can be augmented by the modulation of natural killer (NK) cell and cytokine activity using a mouse tumor model. Walker-256 cells were injected into the right flank of male BALB/c mice. At 7 days after inoculation, mice were divided into three groups, including group 1,2,3. In group 1 the mice were without radiation, in group 2 the mice were received 2 Gy radiation only, and in group 3 the mice were radiated with a priming dose of 75 mGy followed by 2 Gy radiation after 24 h. On day 21 following the radiation, the tumors were removed and the tumor index (tumor weight as a percentage of body weight) was calculated. At 1, 7, 14 and 21 days following the 2 Gy radiation, mouse splenocytes were isolated to analyze the NK activity and measure the production of the cytokines interleukin-1β, interferon-γ and tumor necrosis factor-α by ELISA. Apoptosis was also measured by flow cytometry. The results demonstrated that priming radiation significantly delayed the tumor growth and prolonged the median survival time to 38 days compared with the 31-day survival in the 2 Gy radiation group. The percentage of apoptotic cells was significantly higher in the mice that received 75 mGy + 2 Gy radiation compared with that in the mice that received 2 Gy alone; by contrast, mice that were not irradiated exhibited a relatively low level of apoptosis. The primed mice had a higher level of NK activity as compared with the mice exposed to 2 Gy radiation only or mice that were not irradiated. Furthermore, cytokine expression remained at a higher level in mice receiving priming dose of radiation compared that in the mice receiving only 2 Gy radiation. In conclusion, the results indicated that low-dose priming X-ray radiation may enhance the NK activity and the levels of cytokines, and that the immune response serves an important role in anticancer therapy, including radiotherapy.

Objective To explore the feasibility of using fluorescence in situ hybridization (FISH) technology to detect the Calyculin A (CA)-induced prematurely condensed chromosome(PCC) after high-dose irradiation of X-rays.Methods Human peripheral blood was irradiated by X-rays at 0,1,5,10,15 and 20 Gy.Whole blood was cultured with RPMI 1640 medium,thereafter the CA was used to induce premature chromosome condensation.The No.1 and No.4 whole chromosome probe was used in the FISH,and the chromosomes were observed under the fluorescence microscope.The aberration positive cell quantity and the quantity of fragments of two chromosomes were counted,and dose-effect curve fitted was performed.Results The ratio of chromosomal aberration positive cells had a good dose response (0-15 Gy) with an equation Y =0.008 + 0.065D + 1.858 × 10-5D2 (R2 =0.994).The PCC fragments also had a good dose response within 0-20 Gy with an equation Y=-0.032 +0.216D-0.01D2(R2 =1.0).Conclusions Analysis of Calyculin-A-induced PCC by using FISH technique could be used to estimate the biological dose after high-dose irradiation.

Objective To observe the consistency of T-cell receptor (TCR) genes mutation in lymphocytes in rats after irradiation in vivo and in vitro.Methods A total of 48 female rats were randomly divided into 6 equal groups.Peripheral blood samples from them were collected to separate the lymphocytes and then irradiated to X-ray irradiation with the dose rate of 200 cGy/min at the doses of 0,0.5,0.75,1.0,2.0,and 3.0 Gy,respectively.Then all the lymphocyte samples were cultured for 7 days.Flow cytometry with direct immunofluorescence was used to detect the TCR gene mutation.The levels of TCR gene mutant frequency (TCRMF) of different groups were calculated.Results The TCRMF levels of different groups after irradiation in vivo and in vitro all displayed a dose-dependent manner and there were no significant differences in the TCRMF between different dose irradiation groups(t = -1.1-0.3 ,P ＞0.05).Conclusions A consistency of TCRMF after irradiation in vivo and in vitro is proven.The results of TCRMF of peripheral blood lymphocytes irradiated in vitro by flow cytometry can precisely reflect the TCR genes mutation after whole-body irradiation.

objective To study the TCR gene mutation in peripheral blood lymphocytes induced by X-ray exposure using cultured lymphocytes cloning method.Methods Freshly isolated peripheral lymphocytes from healthy aduh donors were irradiated with X-ray in doses ranging from 0 to 8 Gy and cultured with interleukin2 and phytohemagglutinin for 7 days.The mutant frequencies of TCR gene(TCR MF)were detected by flow cytonletry and the dose response curves were fitted.Results TCR MF increased with the dose going up.An aquadratic polynomial dose response model was fitted.Conclusions TCR gene mutation could which serve as a potential biological dosimeter.It might be applied for the estimation of biological dose in emergency exposure.