Changes in the distribution and function of leukocytes after whole-body iron ion irradiation

Abstract

High-energy particle radiation could have a considerable impact on health during space missions. This study evaluated C57BL/6 mice on Day 40 after total-body 56Fe26+ irradiation at 0, 1, 2 and 3 gray (Gy). Radiation consistently increased thymus mass (one-way ANOVA: P < 0.005); spleen, liver and lung masses were similar among all groups. In the blood, there was no radiation effect on the white blood cell (WBC) count or major leukocyte types. However, the red blood cell count, hemoglobin, hematocrit and the CD8+ T cytotoxic (Tc) cell count and percentage all decreased, while both the CD4:CD8 (Th:Tc) cell ratio and spontaneous blastogenesis increased, in one or more irradiated groups compared with unirradiated controls (P < 0.05 vs 0 Gy). In contrast, splenic WBC, lymphocyte, B cell and T helper (Th) counts, %B cells and the CD4:CD8 ratio were all significantly elevated, while Tc percentages decreased, in one or more of the irradiated groups compared with controls (P < 0.05 vs 0 Gy). Although there were trends for minor, radiation-induced increases in %CD11b+ granulocytes in the spleen, cells double-labeled with adhesion markers (CD11b+CD54+, CD11b+CD62E+) were normal. Splenocyte spontaneous blastogenesis and that induced by mitogens (PHA, ConA, LPS) was equivalent to normal. In bone marrow, the percentage of cells expressing stem cell markers, Sca-1 and CD34/Sca-1, were low in one or more of the irradiated groups (P < 0.05 vs 0 Gy). Collectively, the data indicate that significant immunological abnormalities still exist more than a month after 56Fe irradiation and that there are differences dependent upon body compartment.

Impact of Particle Irradiation on the Immune System: From the Clinic to Mars

“…These investigations have shown that simulated cosmic radiation decreases the lymphocyte population ( 52 ), with a higher impact on B cells, followed by T cells (CD8+ > CD4+) and natural killer cells ( 53 – 55 ). The response and function of leukocytes are also altered by simulated cosmic radiation ( 55 ), and the effects are long lasting and dependent on the dose, the type of source, and the body compartment ( 56 – 59 ). Overall, these results are supported by investigations from other groups ( 60 , 61 ).…”

Radiotherapy and immune response: the systemic effects of a local treatment

“…Sublethal doses delivered with carbon ion beams inhibited in vitro angiogenesis 67 and the expression of angiogenesis mediators 68 , 69 . In immune-competent mouse models, lung metastasis was significantly suppressed by carbon ion irradiation 66 , 70 .…”

The Role of Protein Kinase Activators and ZFN in Reducing the Harmful Effects of Total Body Irradiation

“…2-Other studies indicated a clear decrease in CD8 count, and thus a clear increase in CD4:CD8 rate. [13] Where CD4 is more resistant to radiation at 2-Gray dose than CD8, but CD8's return to normal levels is faster than CD4's [14]. This theory proved to be striking, and after a time of exposure to nuclear bomb radiation, there was a clear variability in the cell count, with a normal CD4 cell count and a decrease in CD8 cell count in the exposed organisms [15] Plus, with the exception of only one report, the CD4 cell count increased in people exposed to radiation in the Chernobyl tragedy [15].…”