31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016): part two

Abstract

Background Exercise immunology has become a growing field in the past 20 years, with an emphasis on understanding how different forms of exercise affect immune function. Overexertion may lead to suppressed immune function whereas moderate exercise may improve immunity. The improvement of immune function through exercise may benefit cancer patients receiving immunotherapy. To begin to test this hypothesis, we investigated the effects of acute and endurance exercise on the composition of peripheral blood leukocytes over time in a healthy male population of varying fitness. Methods Fifteen males participated in two cycling bouts; a short incremental exercise test to exhaustion on one visit and a 45 minute endurance exercise test (cycling at 60 % maximum workload) on the second visit. Lean body mass (LBM) and percent body fat (%BF) were calculated from DEXA (Dual-energy X-ray absorptiometry) scan on study visit 1. Flow-volume curves (FVC) were also collected on visit 1 with the average of 3 attempts within 150 mL of each other. Blood was collected at pre-exercise, immediately post-exercise, 3 hours postexercise, and 24 hours post-exercise. Leukocytes were measured by multi-parameter flow cytometry of more than 50 immunophenotypes for each collection sample. Results We found a differential induction of leukocytosis dependent on exercise intensity and duration. Cytotoxic natural killer cells demonstrated the greatest increase (average of 5.6 fold) immediately post-maximal exercise whereas CD15+ granulocytes demonstrated the largest increase at 3 hours post-maximal exercise (1.6 fold). The longer, less intense endurance exercise resulted in an attenuated leukocytosis. Induction of leukocytosis did not differ in our limited study of active (n = 10) and sedentary (n = 5) subjects to exercise although we found that in baseline samples, sedentary individuals had elevated percentages of CD45RO+ memory CD4+ T cells and elevated proportions of CD4+ T cells expressing the negative immune regulator programmed death-1 (PD-1). Finally, we identified several leukocytes whose presence correlated with obesity related fitness parameters. Conclusions Taken together, our data suggests pre-existing compositional differences of leukocytes based on fitness and rapid and specific accumulation of leukocytes subsets into the blood dependent on the intensity and duration of to exercise.