Exercise-induced lymphocyte apoptosis: Effects of the cell isolation process, exercise intensity, gender, and the menstrual cycle

James Wilfred Navalta, Purdue University

Abstract

The purpose of the current study was to assess the effect of exercise on lymphocyte cell death (apoptosis). Specifically, the effect of lymphocyte isolation on exercise-induced apoptosis was assessed, as well as the level of exercise intensity needed to initiate cell death. In addition, gender differences and the effect of the menstrual cycle were evaluated. Fourteen healthy, untrained individuals (7 men, 7 women) performed two incremental treadmill tests to exhaustion. Women completed the exercise tests during the follicular phase and mid-luteal phases of the menstrual cycle, while men had similar lengths of time between the maximal exercise tests. Blood was sampled by venipuncture before and immediately after exercise, and by finger-stick at the end of each stage and at 20-minute intervals for one hour following each bout. Samples were stained with May-Grünwald Giemsa and apoptotic lymphocytes were assessed morphologically. No differences in the lymphocyte apoptotic response were observed between men and women, or between phases of the menstrual cycle in women. It was determined that exercise intensity near 60% VO2max was sufficient to induce significant increases in apoptosis above baseline values. Increases in exercise-induced lymphocyte cell death were transient however, with levels returning to resting values by 1-h following the bout. Significantly less apoptosis was observed in post-exercise samples that were subjected to an isolation procedure when compared to whole blood (P < 0.0001). Similarly, samples that were drawn and allowed to sit before centrifugation (time-treated) exhibited significantly less apoptosis than whole blood samples (P < 0.0001). These results indicate that the amount of time between post-exercise blood sampling and the assessment of apoptosis is critical for the determination of exercise-induced lymphocyte apoptosis. Because apoptosis is a rapid process, it is likely that any significant delay reduces the percentage of cells that may be considered apoptotic. Findings of the current study show that exercise-induced lymphocyte apoptosis is similar between untrained men and women, and that significantly elevated estrogen levels in women does not alter the response.

Degree

Ph.D.

Advisors

Sedlock, Purdue University.

Subject Area

Immunology|Sports medicine|Anatomy & physiology|Animals

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