A Murine Model for Studying the Effects of Prolonged Space Flight on the Cells of the Immune System

Abstract

The anti-orthostatic suspension mouse model is vital to observing changes within the blood over a long period of time of microgravity. Blood samples were analyzed by flow cytometry to observe the effects of the suspension phenotype and function of the lymphocyte populations over five weeks. After the mice were removed from the suspension, blood samples were taken for another two weeks to monitor the normalization of the immune system. The concentration of nucleated cells found in the blood dropped dramatically during suspension and then rose back to normal after removal from the suspension. The phenotypic populations most affected by the suspension model were the T cell and NK cell populations. The T to NK cell ratio was greatly affected right after suspension and then again after removal from suspension. During the suspension, however, the ratio stayed within the normal range predicted by Time 0. There were no significant changes found in the B cell populations nor in the functional data. Throughout suspension the ratio of T cell and NK cells adapts to the change in environment, however the number of cells available continually drops, possibly leading to the symptoms of immunosuppression described by previous research.