Lymphocyte Phenotype Alterations, Pro-Inflammatory Cytokines and Acute Phase Proteins Following Repeated Bouts of Mountainous Hill-Running

Abstract

We have previously shown that a single bout of exercise elicits a preferential mobilisation and subsequent extravasation of blood lymphocyte subsets expressing high levels of adhesion/activation (AA) molecules and low levels of complement regulatory proteins (Simpson et al. Med. Sci. Sports Exerc. 37, S336, 2005). Repeated bouts of exercise have the potential to accumulatively alter the trafficking of lymphocyte subset populations in the blood compartment. PURPOSE: To examine the effects of repeated bouts of mountainous hill-running on: blood lymphocyte subset counts; lymphocyte cell surface expression of glycoproteins; and plasma concentrations of TNFα and the acute phase proteins CRP, α-1-ACT, fibrinogen, fibronectin and haptoglobin. METHODS: Seven trained males (Age: 28±4yrs,: VO2max: 64 ± 3 ml·kg·mn−1) completed four bouts of hill-running on four consecutive days. Each bout consisted of 1126m ascent/descent over a distance of 24.5km and took 2–2.5h to complete. Blood samples were collected before, immediately after, 1h after completion and 24h after the start of each bout. Isolated lymphocytes were assessed for cell surface expression of subset markers (CD3, CD4, CD8, CD56), AA molecules (CD18, CD53, CD54), complement regulatory proteins (CD55, CD59) and the cell surface death receptor CD95 by flow cytometry. RESULTS: No statistical differences in run time or heart rate were found among the four exercise bouts. For all bouts, total lymphocyte counts and lymphocyte subset counts did not change immediately after exercise. At 1h post-exercise, CD3+, CD4+, CD8+ and CD56+ lymphocytes and the CD3+, CD8+ and CD56+ lymphocytes expressing CD18bright, CD53bright, CD54+, CD55dim, CD59dim and CD95 fell below the pre-exercise value after the first two bouts only. Lymphocyte subset counts and phenotypes returned to the pre-exercise values 24h after all bouts. Plasma CRP concentrations increased 24h after the first bout and remained elevated throughout the subsequent bouts. No changes in plasma concentrations of TNF? or the other acute phase proteins were found. CONCLUSION: Four consecutive days of hill-running elicited marked reductions in the number of lymphocyte subset populations expressing high levels of AA molecules and low levels of complement regulatory proteins. This effect occurred only after the first two exercise bouts, suggesting that a possible “carry-over” effect on lymphocyte trafficking during the subsequent exercise bouts occurred. Basal lymphocyte counts and phenotype characteristics, however, appeared to be restored in the blood compartment after 24h of recovery despite sustained elevations in plasma CRP activity.