Effects on expression levels of surface immune molecules on T cell subsets in spleens and mesenteric lymph node of mice irradiated by 60Co γ-ray lethally total body irradiation

Abstract

Objective To explore the effects of 60Co γ-ray lethally total body irradiation (TBI) on activated molecules and adhesion molecules of T cells from mice spleens and mesenteric lymph nodes. Methods From July to October 2012, a total of 12 male BALB/c mice of specefic pathogen free (SPF) level were selected as experimental objects. Inclusion criteria of experimental objects were 10 to 12 week-ages and 20 to 25 g weight. The mice were divided randomly into TBI group (accepted lethally TBI) and control group (not accepted irradiation), 6 mice per group. TBI group mice were exposure to 60Co γ-ray for one time (dosage rate was 0.66 Gy/min and total dose was 7.5 Gy). All the mice were killed by broken spines on the 7th days after irradiation and obtained spleens and mesenteric lymph nodes. Spleens and mesenteric lymph nodes were ground and mononuclear cells were collected using density gradient centrifugation. The mononuclear cells were stimulated and cultured, then labelled with antibodies. The expressions of CD44 and CD62L on CD4+ T, CD8+ T, helper T cell (Th) 1 and cytotoxic T cell (Tc) 1 were detected by flow cytometry. And the levels of above immune molecules of two group were analysed by statistical methods. Results On the 7th days after irradiation, in TBI group, percentages of CD44+ CD4+ T cell were (88.1±1.1)% in spleen and (76.7±1.8)% in mesenteric lymph node, which were lower than those in control group [spleen (95.0±1.1)% and mesenteric lymph node (92.8±1.4)%] (t=-11.01, -17.82; P 0.05). In TBI group, percentages of CD44+ Tc1 [spleen (65.5±4.6)% and mesenteric lymph node (26.6±2.8)%] were higher than those in control group [spleen (41.8±1.5)% and mesenteric lymph node (18.7±1.3)%] (t=9.97, 6.51; P<0.05). The expressions of CD62L in spleens and mesenteric lymph nodes CD4+ T and CD8+ T cells of TBI group were lower than those of control group [spleen (0.3±0.0)% vs (66.7±4.7)%, (1.1±0.2)% vs (64.4±5.1)%, t=-24.52, -21.53, P<0.05; mesenteric lymph node (2.6±0.3)% vs (89.7±2.8)%, (9.1±0.5) vs (79.4±3.3)%, t=-53.75, -36.55, P<0.05]. Conclusions T cells in spleens and mesenteric lymph nodes were activated with immunotype changes after TBI, manifesting as increased activated molecule CD44 expression and down regulated adhesion molecule CD62L expression on effector T cells. The expression levels of CD44 and CD62L might be indicators of activation of T cells and reflection of functional status of T cells after TBI. Key words: Whole-body irradiation; CD8-positive T-lymphocytes; CD4-positive T-lymphocytes; T-lymphocyte subsets; Phenotype