Effect of Long-Term Space Flight on Human T-Cell Immunity Formation and Development

The results of the study of dendritic cell (DC) maturation processes generated from CD14+monocytes and TCR activation of peripheral blood lymphocytes of 9 Russian crew members of long-term expeditions to the International Space Station (ISS) are presented. It has been shown that human exposure to long-term space flight in low Earth orbit leads to dysfunctions in both DC and T-lymphocytes, as it is evidenced by a decrease in the content of mature DC expressing B7 family co-stimulation molecules and T-lymphocytes expressing CD28 positive co-stimulation molecules. The study revealed an increase in the number of tolerogenic DC with the CD80+CD86– immunophenotype and T-cells expressing the negative co-stimulation molecule CD152. Against the background of lymphocyte TCR-stimulation in vitro, there were determined changes in processes associated with T-lymphocyte differentiation and synthesis of cytokines. Individual highly variable immune system response to prolonged exposure to the complex factors of space flight was noted.