Leukocytosis, muscle damage and increased lymphocyte proliferative response after an adventure sprint race

Abstract

The effect of an adventure sprint race (ASR) on T-cell proliferation, leukocyte count and muscle damage was evaluated. Seven young male runners completed an ASR in the region of Serra do Espinhaço, Brazil. The race induced a strong leukocytosis (6.22±2.04×10(3) cells/mm3 before vs 14.81±3.53×10(3) cells/mm3 after the race), marked by a significant increase of neutrophils and monocytes (P<0.05), but not total lymphocytes, CD3+ CD4+ or CD3+ CD8+ cells. However, the T-cell proliferative response to mitogenic stimulation was increased (P=0.025) after the race, which contradicted our hypothesis that ASR, as a high-demand competition, would inhibit T-cell proliferation. A positive correlation (P=0.03, r=0.79) was observed between the proliferative response of lymphocytes after the race and the time to complete the race, suggesting that the proliferative response was dependent on exercise intensity. Muscle damage was evident after the race by increased serum levels of aspartate amino transferase (24.99±8.30 vs 50.61±15.76 U/L, P=0.003). The results suggest that humoral factors and substances released by damaged muscle may be responsible for lymphocyte activation, which may be involved in muscle recovery and repair.

Figure 1. Analysis of cell proliferation using carboxyfluorescein succinimidyl ester (CFSE) by flow cytometry. A, Control for unstimulated cultures; B, phytohemagglutinin-stimulated cultures; C, CFSE-stained cells derived from unstimulated cultures; D, CFSE-stained cells in cultures stimulated with PHA. SSC and FSC = side and forward scatter, respectively.

Figure 2. Plasma levels of AST (A) but not of ALT (B) were elevated after an adventure sprint race. Data are reported as means±SD. AST: aspartate amino transferase; ALT: alanine amino transferase. *P<0.05, compared to before race (Student paired t-test).

Figure 3. Correlation between lymphocyte proliferative response (proliferation index) and time to complete race. Data are reported as means±SD (dotted lines).