Biological System
Immune & Inflammatory Response
How the body's defense system shifts during spaceflight
Overview
The immune system is the body's defense network — a complex web of cells and proteins that identify and neutralize threats. During spaceflight, this system undergoes measurable shifts. The Inspiration4 crew showed changes in circulating cytokine levels, white blood cell composition, and T/B-cell receptor repertoire diversity, all measured at multiple timepoints before, during (proxied by R+1), and after the 3-day mission.
How to read this page: These findings describe four individuals at one point in time. No finding should be generalized to spaceflight health broadly. Individual differences dominate the signal. Values labeled “2× individual baseline” use derived thresholds, not clinical cutoffs.
Key findings
- Cytokine levels (TNFα, IL-6, IL-1β) showed individual-specific trajectories — no uniform crew-wide pattern.crew who showed this effect
- TCR clonal diversity, measured via VDJ repertoire sequencing, shifted acutely at R+1 and began recovering by R+45.crew who showed this effect
- WBC and neutrophil counts tracked similarly to known short-duration spaceflight patterns.crew who showed this effect
- All observations reflect direction of change from each individual's own pre-mission level — not a population reference.crew who showed this effect
Individual trajectories
change from own pre-mission level · n=4fold-change from L-44BAS
Absolute Basophils
A rare immune cell whose count rises during allergic reactions and inflammation.
Lines show each crew member's change from their own pre-mission level. Shaded band = typical reference range from OSD-575 data files.
EOS
Absolute Eosinophils
Immune cells that fight parasites and allergens — spaceflight radiation tends to suppress them.
Lines show each crew member's change from their own pre-mission level. Shaded band = typical reference range from OSD-575 data files.
LYM
Absolute Lymphocytes
The immune cells that remember past infections; a pre-launch surge is a well-known sign of physical stress.
Lines show each crew member's change from their own pre-mission level. Shaded band = typical reference range from OSD-575 data files.
MON
Absolute Monocytes
Immune patrol cells that clean up damaged tissue; a sustained rise suggests ongoing inflammation.
Lines show each crew member's change from their own pre-mission level. Shaded band = typical reference range from OSD-575 data files.
NEU
Absolute Neutrophils
The immune system's first responders — their count spikes quickly whenever the body detects stress or infection.
Lines show each crew member's change from their own pre-mission level. Shaded band = typical reference range from OSD-575 data files.
BAS%
Basophil Percentage
The share of white blood cells that are basophils, showing how much of the immune response involves this rare cell type.
Lines show each crew member's change from their own pre-mission level. Shaded band = typical reference range from OSD-575 data files.
EOS%
Eosinophil Percentage
The percentage of white blood cells dedicated to fighting allergens and parasites.
Lines show each crew member's change from their own pre-mission level. Shaded band = typical reference range from OSD-575 data files.
LYM%
Lymphocyte Percentage
The share of white blood cells that are lymphocytes — the adaptive, 'memory' arm of the immune system.
Lines show each crew member's change from their own pre-mission level. Shaded band = typical reference range from OSD-575 data files.
MON%
Monocyte Percentage
The percentage of white blood cells that are monocytes — the immune system's patrol and clean-up crew.
Lines show each crew member's change from their own pre-mission level. Shaded band = typical reference range from OSD-575 data files.
NEU%
Neutrophil Percentage
The share of white blood cells that are neutrophils — typically the largest fraction and the immune system's front line.
Lines show each crew member's change from their own pre-mission level. Shaded band = typical reference range from OSD-575 data files.
WBC
White Blood Cell Count
The total count of all immune cells in the blood — a barometer for how hard the body's defenses are working.
Lines show each crew member's change from their own pre-mission level. Shaded band = typical reference range from OSD-575 data files.