McGill Jodi L, Sacco Randy E
Department of Diagnostic Medicine and Pathobiology, Kansas State University, 1800 Denison Ave., Manhattan, KS 66503, USA.
Ruminant Diseases and Immunology Research Unit, National Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, 1920 Dayton Ave., Ames, IA 50010, USA.
Vet Immunol Immunopathol. 2016 Nov 15;181:24-29. doi: 10.1016/j.vetimm.2016.02.012. Epub 2016 Feb 21.
γδ T cells are a subset of nonconventional T cells that play a critical role in bridging the innate and adaptive arms of the immune system. γδ T cells are particularly abundant in ruminant species and may constitute up to 60% of the circulating lymphocyte pool in young cattle. The frequency of circulating γδ T cells is highest in neonatal calves and declines as the animal ages, suggesting these cells may be particularly important in the immune system of the very young. Bovine respiratory syncytial virus (BRSV) is a significant cause of respiratory infection in calves, and is most severe in animals under one year of age. BRSV is also a significant factor in the development of bovine respiratory disease complex (BRDC), the leading cause of morbidity and mortality in feedlot cattle. Human respiratory syncytial virus (RSV) is closely related to BRSV and a leading cause of lower respiratory tract infection in infants and children worldwide. BRSV infection in calves shares striking similarities with RSV infection in human infants. To date, there have been few studies defining the role of γδ T cells in the immune response to BRSV or RSV infection in animals or humans, respectively. However, emerging evidence suggests that γδ T cells may play a critical role in the early recognition of infection and in shaping the development of the adaptive immune response through inflammatory chemokine and cytokine production. Further, while it is clear that γδ T cells accumulate in the lungs during BRSV and RSV infection, their role in protection vs. immunopathology remains unclear. This review will summarize what is currently known about the role of γδ T cells in the immune response to BRSV and BRDC in cattle, and where appropriate, draw parallels to the role of γδ T cells in the human response to RSV infection.
γδ T细胞是非传统T细胞的一个亚群，在连接免疫系统的固有免疫和适应性免疫分支方面发挥着关键作用。γδ T细胞在反刍动物中尤为丰富，在幼年牛的循环淋巴细胞池中可能占高达60%。循环γδ T细胞的频率在新生犊牛中最高，并随着动物年龄的增长而下降，这表明这些细胞在幼小动物的免疫系统中可能特别重要。牛呼吸道合胞病毒（BRSV）是犊牛呼吸道感染的一个重要原因，在一岁以下的动物中最为严重。BRSV也是牛呼吸道疾病综合征（BRDC）发展的一个重要因素，BRDC是育肥牛发病和死亡的主要原因。人类呼吸道合胞病毒（RSV）与BRSV密切相关，是全球婴幼儿下呼吸道感染的主要原因。犊牛的BRSV感染与人类婴儿的RSV感染有显著相似之处。迄今为止，很少有研究分别确定γδ T细胞在动物或人类对BRSV或RSV感染的免疫反应中的作用。然而，新出现的证据表明，γδ T细胞可能在感染的早期识别以及通过炎症趋化因子和细胞因子的产生来塑造适应性免疫反应的发展中发挥关键作用。此外，虽然很明显γδ T细胞在BRSV和RSV感染期间会在肺部积聚，但其在保护与免疫病理学中的作用仍不清楚。本综述将总结目前已知的γδ T细胞在牛对BRSV和BRDC免疫反应中的作用，并在适当情况下，将γδ T细胞在人类对RSV感染反应中的作用与之进行比较。
