Abstract: OBJECTIVE: To explore effects on the percentages and numbers of Ly6C⁺ and Ly6C^- monocyte subsets from peripheral blood of irradiated mice. METHODS: After exposure to 4 Gy γ rays, mice were subdivided into 10 mice per group and evaluated at 3, 5, 7, 14 and 21 days after the irradiation. There were also 10 non-irradiated control mice. The number of monocytes from peripheral blood of irradiated mice was measured by blood cell analysis instrument. The percentage of Ly6C⁺ and Ly6C^- monocyte subsets was detected by flow cytometer. RESULTS: At 3, 5 and 7 days after the irradiation, the numbers of monocyte subsets were significantly decreased (P<0.01) compared to those from the controls. The Ly6C⁺ monocyte subsets fromthe fifth day group were significantly higher than those from the third day group (P<0.01), but significantly decreased (P<0.01) compared to the seventh day group. Compared with control group, the percentages of Ly6C⁺ monocyte subsets from the third and fifth day groups were significantly increased to 90% and the percentage of Ly6C^- monocyte subsets were significantly decreased to 10%. In addition, both the numbers and percentages of monocyte subsets from the fourteenth day group were significantly decreased (P<0.01) compared to the controls. On the other hand, both the numbers and percentages of monocyte subsets recovered at 21 day after irradiation. CONCLUSION: During the first week after irradiation, the numbers of monocyte subsets from peripheral blood of mice were reduced significantly. The decrease may be associated with radiation-induced apoptosis of these monocyte subsets.

Key words: ionizing radiation, monocyte subsets, peripheral blood, flow cytometry