Physical fitness modulates the expression of CD39 and CD73 on CD4⁺ CD25^- and CD4⁺ CD25⁺ T cells following high intensity interval exercise.

AIM:To investigate the impact of physical fitness on the mobilization of CD4⁺ CD25 ^- CD39 ⁺ and CD4 ⁺ CD25 ⁺ CD39 ⁺ T cells in response to acute exercise. METHODS:Fifteen high physical fitness (25.3 ± 1.4 years) and 15 low physical fitness (26.1 ± 1.9 years) men performed a single bout of high-intensity interval exercise (HIIE, 10 bouts of 60 seconds at 85% HRmax intercepted by 75 seconds of recovery at 50% HRmax). Blood lymphocytes were isolated before, immediately after and 1 hour after exercise for assessment of cell surface expression of CD25, CD39, and CD73 on CD4⁺ T cells. Effector memory T cells (mTeff) were identified by CD4 ⁺ CD25 ^- CD39 ⁺ coexpression, and memory regulatory T cells (mTReg) were defined as CD4 ⁺ CD25 ⁺ CD39 ⁺ T cells. RESULTS:Exercise increased CD4⁺ and CD4 ⁺ CD25 ⁺ T cell frequencies immediately after followed by a decrease bellow to baseline values at 1 hour after the bout in both low and high physical fitness groups. At baseline, the proportions of mTeff were higher, while mTreg were lower in low physical fitness individuals. The frequency of mTreg increased immediately after HIIE in both groups, and remained higher 1 hour after the bout. However, high physical fitness individuals presented higher mTreg frequency in all periods evaluated. A significantly mobilization of mTeff cells was identified in both groups immediately after HIIE. High physical fitness individuals displayed a decrease in mTeff cells bellow to baseline, while the frequency of mTeff remained higher in low physical fitness group 1 hour after the bout. The peripheral frequency of CD4 ⁺ CD25 ⁺ CD73 ⁺ T cells increased in a similar way immediately after the bout in both groups, returning to the baseline values 1 hour after exercise. No differences in CD4 ⁺ CD25 ^- CD73 ⁺ T cells were observed after HIIE in both groups. CONCLUSION:Our results highlight the impact of physical activity status in the redistribution of CD4⁺ T cells expressing ectonucleotidases in response to HIIE.

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