The effect of space flight on human cellular immunity

Area of Science:

• Immunology
• Space Medicine
• Human Physiology

Background:

• Spaceflight poses unique challenges to the human immune system.
• Previous studies indicate potential alterations in immune function during and after space missions.
• Understanding these changes is vital for astronaut health and mission success.

Purpose of the Study:

• To assess the impact of spaceflight on T-lymphocyte responsiveness.
• To investigate the effects of spaceflight stressors on immune function.
• To evaluate immune responses using T-lymphocyte and skin tests in astronauts.

Main Methods:

• Measured T-lymphocyte responsiveness to mitogens in astronauts before, during, and after spaceflight.
• Compared spaceflight immune data with data from subjects under physical stress (head-down tilt bedrest).
• Assessed delayed hypersensitivity response using a skin test on space shuttle and MIR orbital station crews.

Main Results:

• T-lymphocyte responsiveness decreased by an average of 56% in 129 subjects during and after spaceflight.
• Delayed hypersensitivity response was reduced in 14 out of 15 tested astronauts.
• In-flight immune depression correlated with physical and psychological stress in some cases.

Conclusions:

• Spaceflight factors including stress, confinement, and radiation may impair immune responsiveness.
• Observed immunological changes warrant further investigation for long-duration space missions.
• While not currently harmful, immune alterations require understanding for future lunar and Martian exploration.