Microgravity Inhibits Resting T Cell Immunity in an Exposure Time-Dependent Manner

licenses/by-nc-nd/3.0/). Reproduction is permitted for personal, noncommercial use, provided that the article is in whole, unmodified, and properly cited. Received: 2013.09.12; Accepted: 2013.12.11; Published: 2013.12.21 Background: Decline immune function is well documented after spaceflights. Microgravity is one of the key factors directly suppressing the function of immune system. Though T cell immune response was inhibited by microgravity, it is not clearly whether activation would be inhibited after a pre-exposure of microgravity on T lymphocytes at the resting state. Methods: We herein in-vestigated the response ability of resting CD4+ and CD8+ T cells experiencing pre-exposure of modeled microgravity (MMg) for 0, 8, 16 and 24 hrs to concanavalin A (ConA) stimulation. The phenotypes and subsets of immune cells were determined by flow cytometry. Results: Both CD4+ and CD8+ T cells with an MMg pre-exposure exhibited decreased expressions of activa-tion-markers including CD25, CD69 and CD71, inflammatory cytokine secretion and cell prolif-eration in response to ConA compared with T cells with 1g controls in an MMg exposure time-dependent manner. Moreover, short term MMg treatment caused more severe decreased pro-liferation in CD4+ T cells than in CD8+ T cells. Conclusions: MMg can directly impact on restin