Edinburgh Napier University

  PURPOSE: Although it is known that peripheral blood lymphocytes display an activated phenotype immediately after an acute bout of high-intensity exercise, it is not known if these lymphocytes are activated by exercise or whether this is due to a mobilisation of activated lymphocytes into the blood. To exclude the effects of cell mobilisation and to ascertain whether any serum factors were responsible for exercise-induced lymphocyte activation, this study examined the effects of autologous serum obtained after a 40-km
cycling time-trial on the activation of resting peripheral blood lymphocytes.
METHODS: Eight male cyclists (Age: 30.8 ± 1.5yrs) completed a 40km time-trial on an indoor cycling ergometer (mean completion time 57:06 ± 3:17 min:sec). Resting blood lymphocytes isolated before exercise were incubated in culture for 2h at 37°C with 50% autologous serum obtained before (PRE), immediately after (POST) or 1h (1H) after exercise at a final concentration of 1.5x106
cells/ml. Following incubation, CD3+, CD3+/CD4+ and CD3+/CD8+ T-cells and CD3-/CD56+ NK-cells were assessed for the cell surface expression of the activation markers CD11a, CD11b, CD18, CD25, CD27, CD53, CD62L, CD69, CD95 and CD122 by four-colour flow cytometry.
RESULTS: Total numbers of CD3+, CD4+ and CD8+ T-cells and NK-cells increased immediately after exercise and fell below pre-exercise values 1h later. The cell surface expression of CD11b, CD18bright and CD62L on resting blood NK-cells was 9%, 12% and 13% greater respectively at POST in comparison to PRE. At POST, the expression of CD69 on CD4+ and CD8+ T-cells was 18% and 27% greater respectively than PRE. CD71 expression on CD8+ T-cells increased by 84% at POST. Serum stimulated lymphocytes co-cultured with the mitogen PMA also showed significantly greater levels of CD69 expression at POST in comparison to PRE.
CONCLUSION: Using a wide-range of cell surface activation markers, we found that resting blood lymphocytes are activated by autologous serum after an acute bout of highintensity
endurance exercise. Although the activation levels were modest in comparison to those typically seen in lymphocytes mobilised by exercise, these data could highlight a potential role for serum components on the activation and extravasation of blood lymphocytes in response to acute exercise.