Analysis of Th1-Th2-Th3 related gene expressions in the thymus of mice irradiated with different doses

Objective To analyze the effect of high and low dose radiation on the expressions of Th1, Th2 and Th3 /Tr1 related-genes in mice thymocytes and investigate the possible underlying molecular mechanism. Methods ICR mice were randomly divided into low-dose group (0.075 Gy), high-dose group (2.0 Gy) and sham-control group. The mouse thymus tissue was extracted at 16 hours after irradiation and the expressions of Th1-Th2-Th3 related genes were measured by PCR array. Results Eight genes were up-regulated and five genes were down-regulated after low dose radiation (0.075 Gy); while 54 genes were up-regulated and three genes were down-regulated after high dose (2.0 Gy) radiation. These genes included Th1 cell related genes, Th2 cell related genes, Th3/Tr1 cell related genes, Th1/Th2 immune response genes and transcription factor related genes. Low dose radiation induced up-regulation of Stat4 and Socs1 of genes related to the Th1 cells, and it induced down-regulation of IL-4ra, Cebpb, Gata3 and Tgfb3 associated with Th2 and Th3 cells, which lead to Sftpd genes up-regulation of Th1 immune response eventually. The high dose radiation up-regulated all of Th1, Th2 and Th3/Tr related genes and also enhanced the expressions of Cd86, IL-18, IL-10 and Irf4 genes related to Th2 immune response, but it did not alter the gene expression of Th1 immune response. Conclusions Low-dose radiation induces Th1-type immune response, while high doses radiation triggers Th2 type immune response. Key words: Radiation; Dose; Th cells; PCR array; Immune response