Naive and memory T cell subsets are differentially mobilized during physical stress

Area of Science:

• Immunology
• Exercise Physiology
• Environmental Stress

Background:

• T cell mobilization plays a crucial role in immune surveillance and response.
• Understanding T cell phenotypes during combined physiological stressors like exercise and heat is vital for immune function insights.

Purpose of the Study:

• To investigate the naive and memory phenotypic profiles of CD4+ and CD8hi T cells mobilized during combined aerobic exercise and heat stress.
• To determine the expression of adhesion molecules CD62L and CD11a on these mobilized T cells.

Main Methods:

• Twelve healthy males underwent 40 minutes of cycle ergometry at 65% VO2peak in a 39°C water bath.
• Blood samples were collected pre-exercise, during exercise, and post-exercise.
• Three-color flow cytometry was used to analyze CD4+ and CD8hi T cell expression of CD45RO, CD11a, and CD62L.

Main Results:

• Approximately 80% of mobilized CD4+ T cells exhibited a CD45RO memory phenotype.
• Mobilized CD8hi T cells showed a near-equal recruitment of naive (43%) and memory (57%) cells.
• High expression of CD11a and low expression of CD62L were key factors in CD8hi T cell mobilization.

Conclusions:

• The mobilization of CD4+ T cells during exercise and heat stress is associated with a memory phenotype, not solely explained by CD11a and CD62L expression.
• CD8hi T cell mobilization is independent of memory phenotype but significantly influenced by high CD11a expression and low CD62L expression, indicating altered adhesion and homing receptor function.