Systemic immune changes following meal intake in humans

Area of Science:

• Immunology
• Nutrition Science
• Human Physiology

Background:

• Food intake presents a significant intestinal antigen exposure, necessitating robust host defense mechanisms.
• Both local immune activation and coordinated systemic immune responses are crucial for managing dietary antigens.
• The systemic immune response may play a supportive role in bolstering local intestinal immunity.

Purpose of the Study:

• To investigate the systemic immune response following the consumption of a standardized high-protein meal.
• To assess the impact of a high-protein meal on peripheral blood mononuclear cell counts.
• To evaluate changes in cytokine production (TNF-α, IL-1β, IL-6, IFN-γ) and plasma hormone levels (cortisol, growth hormone).

Main Methods:

• A controlled study involving ten healthy men aged 18-35 years.
• Two experimental sessions: one fasting and one post-high-protein meal.
• Frequent blood sampling (every 15 min) to analyze cell counts, cytokine levels, and hormone concentrations.

Main Results:

• Postprandial increase in neutrophil and platelet counts lasting over 2.5 hours.
• Significant decrease in lymphocyte counts following meal intake.
• Reduced in vitro production of interferon-gamma (IFN-γ) after the meal.
• Elevated plasma cortisol concentrations observed post-meal.
• No significant changes in TNF-α, IL-1β, or IL-6 production or plasma levels.

Conclusions:

• A high-protein meal induces significant systemic immune changes, including altered leukocyte distribution and reduced IFN-γ production.
• These immune alterations are associated with a postprandial increase in plasma cortisol levels.
• The observed changes, such as lymphocyte emigration, may contribute to supporting local intestinal immune defense mechanisms.