PAYLOADS - Human Research
Fighting Infection in Space: Immune System Function and Response
causes changes in the immune system that are not yet fully understood.
Initial studies have identified two areas of change in the immune
system: reactivation of latent (inactive) viruses and suppressed
immune response. The mental stress and closed conditions associated
with spaceflight often decrease the immune response to foreign
organisms like viruses. In the human body, some viruses are present
in a latent state or inactive state, until a condition like stress
causes increased viral activity. This increased viral activity
is a good indicator of how well the immune system is functioning
transmission electron micrograph of the Herpes Simplex Virus
I shows its external envelope (or shell) and genetic material
investigations aim to better understand these immune system changes.
Both studies use blood and urine samples collected during routine
physicals taken before and after the flight. Any changes between
pre- and postflight assessments may indicate altered immune response
as a result of spaceflight. Data will be collected from all crewmembers
before and after the flight. The first investigation, Cell Immunity
and Reactivation of Latent Viral Infections, will determine if
stress induces reactivation of the herpes virus in-flight. White
blood cells, a type of cells that fight infection in the body,
will also be assessed for structural and functional changes that
occur as a result of spaceflight. This mission will add seven
subjects to complement an existing database of 29 crewmembers
from previous shuttle missions.
investigation, Space Flight and Immune Function, will determine
the status of specific immune response elements, whose essential
function may be altered during spaceflight. Changes to typical
infection-fighting cells such as neutrophils, monocytes and cytotoxic
cells will be assessed and then used to define the risk of developing
an infectious disease during long spaceflights. This investigation
is based on earlier spaceflight and ground-based studies.
computer reconstruction reveals the complex protein units
that make up the Herpes Simplex Virus I envelope (Chiu,
Rixon and Zhou at University of Texas, Houston).
underway for establishing a continuously crewed space station,
a healthy immune response becomes more important to mission success.
Increased crew size and mission duration may influence the long-term
immune response of crewmembers, as they are confined to the closed
quarters of the space station for long periods of time. Decreased
immune response is also found in a number of environments on Earth,
where close confines create an environment similar to that found
in a spacecraft. These environments include polar stations, submarines,
hospitals and nursing homes. In particular, the elderly are susceptible
to immune-related diseases and infection because of a decreased
immune cell response that occurs with age. Research into immune
system suppression and infection-fighting response during spaceflight
will provide important insight into patients affected by immune
suppression on Earth.
of us come into contact with some form of infection every day
but we rarely contract an illness because of our healthy immune
response. The Epstein-Barr virus, for example, infects approximately
80-90 percent of the general population, but few people actually
contract the disease because viral activity levels are low. Research
into the regulation of the immune sytem during spaceflight will
add to our understanding of the immune system in general and may
reveal new avenues of research into immune disorders.