Immune changes during short-duration missions

Abstract

Spaceflight materially influences the immune mechanism of humans and animals. Effects resulting from missions of less than 1 month are examined. Effects from longer missions are discussed in the companion paper by Konstantinova et al. Most immunology studies have involved analyses of subjects and samples from subjects obtained after flight, with the data being compared with similar data obtained before flight. These studies have demonstrated that short-duration missions can result in a postflight depression in blast cell transformation, major changes in cytokine function, and alterations in the relative numbers of immune cell populations. In addition to these post- vs. preflight studies, some data have been produced in flight. However, these in vitro analyses have been less than satisfactory because of differences between in-flight and ground-control conditions. Recently, both the U.S. and Russian space programs have started collecting in-flight, in vivo, cell-mediated immunity data. These studies have confirmed that the human cell-mediated immune system is blunted during spaceflight.

Epstein-Barr virus reactivation associated with diminished cell-mediated immunity in Antarctic expeditioners

“…Baseline DTH measurements (under low stress conditions in Australia) were not conducted in our study due to the subjects' unavailability during the desired baseline periods; however, Muller et al [1995b] showed that the diminished DTH responses observed during a 56-day expedition in Antarctica returned to normal values after the subjects returned to Australia. Taylor [1993] reported similar DTH reductions in astronauts during short space flights; Konstantinova et al [1993] found reductions in DTH responses during long space flights.…”

“…Decreased CMI response may lead to viral reactivation, resulting in asymptomatic viral shedding, localized infections, or disseminated infections. Previous studies demonstrated decreased CMI response during space flight [Taylor and Janney, 1992;Taylor, 1993].…”

Suppressed PHA activation of T lymphocytes in simulated microgravity is restored by direct activation of protein kinase C

“…There is a requirement for monocytes in the culture to provide costimulation through both physical contact and soluble factors [26]. The PHA response of astronauts' lymphocytes is suppressed after spaceflight [15,16]. Furthermore, the PHA responsiveness of lymphocytes cultured in clinostatic rotation and true microgravity is suppressed [6-9, 18, 20].…”

“…Astronauts post-flight of long-duration missions have an increase in leukocyte count, decrease in T cell count, decreased mitogeninduced interleukin-2 (IL-2) production, and decreased response to phytohemagglutinin (PHA) [15]. Astronauts postflight of short-duration missions have a decrease in lymphocyte count, increase in neutrophil count, and decreased response to PHA [16]. Astronauts in-flight of both long-and short-duration missions have a reduced delayed-type hypersensitivity skin test response [15][16][17].…”

“…Astronauts postflight of short-duration missions have a decrease in lymphocyte count, increase in neutrophil count, and decreased response to PHA [16]. Astronauts in-flight of both long-and short-duration missions have a reduced delayed-type hypersensitivity skin test response [15][16][17]. Furthermore, in vitro experiments performed in both true and simulated microgravity demonstrate a suppressed response of lymphocytes to mitogens [6][7][8][9][18][19][20].…”