Chemokine Receptor Profile of Circulating Leukocyte Subsets in Response to Acute High-Intensity Interval Training.

NK cells, CD4+ T cells, and γδ T cells were strongly mobilized immediately after HIIT and returned to or below baseline one hour later.

• Sixteen healthy participants completed a single HIIT session.
• Peripheral blood was collected before exercise (Bsl), immediately after (Ex02), and one hour later (Ex60).
• Mobilization was assessed via surface expression of chemokine receptors using flow cytometry.
• Cell counts returned to or below baseline levels at the Ex60 timepoint.

HIIT preferentially mobilized CX3CR1+ CXCR2+ CD56dim NK cells compared to other NK cell subsets.

• CD56dim NK cells expressing CX3CR1 and CXCR2 were disproportionately increased at Ex02.
• This phenotype is associated with migratory and cytotoxic potential.
• FlowSOM clustering was used to identify and characterize NK cell subsets.
• CD56dim NK cells are considered the more cytotoxic and peripherally circulating NK cell subset.

HIIT preferentially mobilized CD4+ T cells expressing CX3CR1hi and CCR5+.

• CD4+ T cells with high CX3CR1 expression and CCR5 positivity were preferentially mobilized at Ex02.
• This chemokine receptor profile is phenotypically associated with migratory and cytotoxic potential.
• Surface expression was measured using flow cytometry followed by FlowSOM clustering.
• These cells returned to or below baseline levels at Ex60.

HIIT preferentially mobilized CX3CR1+ CD56+ γδ T cells.

• γδ T cells expressing CX3CR1 and CD56 were preferentially mobilized at Ex02.
• This phenotype is associated with migratory and cytotoxic potential.
• γδ T cells were strongly mobilized at Ex02 and returned to or below baseline at Ex60.
• FlowSOM clustering was used to identify this γδ T cell subset.

Proportions of intermediate and non-classical monocytes increased immediately after HIIT and decreased one hour later.

• Intermediate and non-classical monocyte proportions increased at Ex02.
• These proportions decreased at Ex60.
• Monocyte subsets were identified using flow cytometry with chemokine receptor surface expression markers.
• FlowSOM clustering was applied to characterize monocyte subset profiles.

The study design involved 16 healthy participants completing a single acute HIIT session with three blood collection timepoints.

• Sample size was 16 healthy participants.
• Blood was collected at three timepoints: before exercise (Bsl), immediately after (Ex02), and one hour after (Ex60).
• Surface expression of selected chemokine receptors was measured using flow cytometry.
• Cell populations analyzed included CD4+ T cells, γδ T cells, NK cells, and monocytes.
• FlowSOM clustering was used for downstream analysis of flow cytometry data.

Physically active individuals demonstrate enhanced immune competence related to chemokine receptor-regulated immune cell trafficking.

• Efficient execution of effector function relies on chemokine receptor-regulated immune cell trafficking along chemokine gradients.
• Trafficking occurs toward sites of inflammation, infection, tumors, or tissue damage.
• This study was motivated by the relationship between physical activity and immune competence.