High-intensity training reduces CD8+ T-cell redistribution in response to exercise

Area of Science:

• Exercise immunology
• Cellular immunology
• Sports science

Background:

• Exercise profoundly impacts immune cell distribution, particularly CD8(+) T lymphocytes (CD8(+)TLs).
• The effects of intensified training on exercise-induced immune responses require further investigation.

Purpose of the Study:

• To determine if high-intensity training impairs exercise-induced lymphocytosis and lymphocytopenia.
• To investigate the impact of training intensity on CD8(+) T lymphocyte (CD8(+)TL) mobilization and egress.

Main Methods:

• Eight trained cyclists completed 1 week of normal-intensity and 1 week of high-intensity training.
• Participants performed a prolonged cycling exercise protocol including submaximal exercise and a time trial.
• Blood samples were analyzed for CD8(+) T lymphocyte (CD8(+)TL) counts and subpopulations (CD45RA, CD27).

Main Results:

• High-intensity training resulted in a smaller exercise-induced mobilization of CD8(+) T lymphocytes (CD8(+)TLs) compared to normal-intensity training.
• The response of highly cytotoxic CD8(+) T lymphocytes (CD8(+)TLs) was significantly reduced after high-intensity training.
• Postexercise CD8(+) T lymphocyte (CD8(+)TL) lymphocytopenia was less pronounced following high-intensity training, primarily due to reduced egress of naive CD8(+)TLs.

Conclusions:

• One week of high-intensity training impairs CD8(+) T lymphocyte (CD8(+)TL) mobilization and egress in response to exercise.
• Reduced mobilization of CD8(+) T lymphocytes (CD8(+)TLs) was linked to blunted neuroendocrine responses (epinephrine, cortisol).
• Impaired CD8(+) T lymphocyte (CD8(+)TL) redistribution may suggest compromised immune surveillance in athletes undergoing intensified training.