Does exercise really induce lymphocyte apoptosis?

James Wilfred Navalta¹, Brian Keith McFarlin^{2, 3}, Thomas Scott Lyons¹

1Department of Kinesiology, Recreation, and Sport; Western Kentucky University; Bowling Green, Kentucky ,²Department of Health and Human Performance; Laboratory of Integrated Physiology; University of Houston; Houston, Texas, ³Department of Health and Human Performance; Texas Obesity Research Center; University of Houston; Houston, Texas

TABLE OF CONTENTS

1. Abstract

2. Introduction

3. Exercise-induced lymphocyte apoptosis

3.1. Animal research

3.1.1. Pathway-directed investigations in cell death

3.1.2. Unequivocal reports

3.2. Human investigations

3.2.1. Morphological investigations

3.2.2. Biochemical findings

4. Limitations with current assessment techniques

4.1. Wide variance between reports

4.2. Lack of an adequate method

5. Considerations for developing a new technique

5.1. Describe the process

5.2. Objectivity

5.3. Discriminate subfractions

5.4. Timing of sampling and processing

5.5. Time and cost effective

5.6. In vivo measures

6. Conclusion

7. References

1. ABSTRACT

While the stress associated with acute exercise has been reported to induce significant lymphocyte apoptosis, not all investigations have confirmed this finding. Regardless of animal or human subjects, exercise-induced lymphocyte apoptosis may be induced via an external receptor-mediated pathway, or internally via the mitochondria through an oxidative-mediated pathway. On the other hand, investigators reporting no effect of acute exercise on lymphocyte apoptosis speculate that cell death may be dissociated from these pathways, and explain exercise lymphocytopenia by selective migration of the lymphocytes back into the lymphoid pools. Discrepancies may be due to sensitivity issues related to the methodology used to assess cell death. Limitations to various methods used to evaluate exercise-induced lymphocyte apoptosis are detailed, and considerations for a new technique are outlined.