Innate Immune Phenotypes During Acute High-Altitude Exposure.

Area of Science:

• Immunology
• High-altitude physiology
• Environmental medicine

Background:

• High altitude presents a physiologically stressful environment due to reduced oxygen availability (hypoxia).
• While physiological adaptations to high altitude are well-studied, the impact on immune function remains less understood.
• Hypoxia during high-altitude travel may influence immune phenotypes through crosstalk with inflammatory pathways.

Purpose of the Study:

• To investigate the effects of acute high-altitude exposure on innate immune cell phenotypes.
• To examine changes in monocyte and neutrophil populations at high altitude.
• To explore the relationship between immune alterations and Acute Mountain Sickness (AMS).

Main Methods:

• Recruited 17 healthy participants for a study at sea level and 3 days at 3,800 m.
• Analyzed immune cell phenotypes, with a specific focus on neutrophils.
• Correlated Acute Mountain Sickness (AMS) scores with observed immune cell shifts.

Main Results:

• Significant shifts in monocyte populations from classical to intermediate and nonclassical subsets were observed.
• Total B cell counts increased during high-altitude exposure.
• Higher AMS scores correlated with more pronounced shifts to nonclassical monocyte populations.

Conclusions:

• Acute high-altitude travel induces a pro-inflammatory immune response, potentially contributing to AMS.
• Immune alterations appear to decrease with acclimatization, though elevated B cells persist.
• Neutrophil CD15 expression was affected by altitude, showing a trend toward increased expression over time.