Effects of Low-Dose Radiation on the Immune System of Mice after Total-Body Irradiation

Abstract

The effects of acute exposure to low- and high-dose radiation on the quantitative and functional parameters of the immune system were analyzed. C57BL/6 mice were irradiated with different doses of γ radiation (0.01, 0.05, 0.1, 0.5 and 2 Gy) and splenocytes were isolated at various times. Alterations in the distribution and surviving fraction of splenocyte subsets such as CD4(+) and CD8(+) T lymphocytes, regulatory T cells (Treg), natural killer (NK) cells, dendritic cells (DCs) and B lymphocytes were analyzed by flow cytometry. Apoptosis frequency was quantified by the TdT-mediated dUTP-biotin nick end labeling (TUNEL) method 4 h after irradiation. Cytokine expression was investigated by real-time reverse transcription-polymerase chain reaction (RT-PCR). Low doses decreased apoptosis in the splenocyte subpopulations studied most prominently in NK cells and DCs. Exposure to 2 Gy increased apoptosis in all splenocyte subpopulations; B cells were the most sensitive and NK cells and DCs the least sensitive. The lowest cell numbers were measured 3 days after irradiation, with minor changes by day 7. CD8(+) and B cells were rather resistant to low doses but were very sensitive to 2 Gy, while NK cells, DCs and Treg cells were much more resistant to high doses. Expression of the T-helper 1 (Th1)- and helper 2 (Th2)-type cytokines decreased after low doses and increased after high doses. Interleukin 6 (IL-6) reacted at early times and IL-10 at later times. IL-5 levels were consistently elevated. These data highlight the differences in the responses of different splenocyte subpopulations to low- and high-dose radiation.

Performance Assessment of a Preclinical PET Scanner with Pinhole Collimation by Comparison to a Coincidence-Based Small-Animal PET Scanner

“…In some cases, injection of a high dose could be problematic. It depends on the ability to produce concentrated tracer, raises the potential for a mass effect (e.g., in receptor studies) (17), and may bring confounds from the absorbed dose received by the mouse (18,19). The applications for which clustered-pinhole PET is superior to coincidence PET are limited but include commonly performed 18 F-FDG imaging.…”

Suppression of CD4+Effector Responses by Naturally Occurring CD4+CD25+Foxp3+Regulatory T Cells Contributes to Experimental Cerebral Malaria

“…However, although the development of a neuropathological immune response and the contribution of host CD4 ϩ T and CD8 ϩ T cells to ECM were preserved, it is difficult to appreciate the whole systemic effects (endothelium, microglia, intestinal flora) in addition to the immunomodulatory effect of low-dose total-body irradiation (35)(36)(37)(38)(39) in our model. Similarly, we are not able to appreciate how the infection and neuropathogenesis could modulate the irradiation effect, which develops over time (35,36).…”

Effects of Low-Dose-Gamma Rays on the Immune System of Different Animal Models of Disease

“…The up-regulation of Treg cells in irradiated mice was also reported in MRL-lpr/lpr mice, used as an animal model for SLE , and EAE mice, used as an animal model for MS . On the other hand, Bogdándi et al (2010) reported no significant change in the percentage of CD4 + CD25 + Foxp3 + Treg cells in normal C57BL/6 mice after one single 0.5Gy γ-irradiation. A difference may exist between normal mice and disease mouse models.…”

“…The effects of low-dose irradiation on the immune system were examined by determining time-dependent numerical changes in various lymphocyte subsets (Bogdándi et al 2010 …”