Purpose: To determine whether exercise training would increase lymphocyte activation in patients with breast cancer following chemotherapy. Activation was determined by the presence of CD4+CD69+ T-helper lymphocytes, mitogen-induced proliferation, and levels of cytokines produced by mitogen-stimulated lymphocytes and in the patients' plasma.
Methods: Patients with breast cancer (N = 28) who participated in a 6-month exercise program were compared with patients (N = 21) who did not exercise. Following chemotherapy, and 3 and 6 months later, patients underwent fitness evaluations and had blood drawn. The exercise program consisted of resistance training and aerobic activity at 60-75% functional capacity three times a week with a personal trainer. Immunochemistry and flow cytometry were used to measure the number of CD4+CD69+ blood lymphocytes. Whole blood was stimulated with concanavalin A (ConA), phytohemagglutin (PHA), or pokeweed mitogen (PWM) to determine proliferation potential. Enzyme-linked immunosorbent assays (ELISA) were used to determine the concentration of interferon-gamma (IFN-γ) and interleukin-6 (IL-6) in the culture medium of mitogen-stimulated lymphocytes as well as the plasma concentrations of IL-6, soluble IL-6 receptor, soluble gp130, and IFN-γ. Analysis of groups across time was done using the Wilcoxon signed rank test, and comparisons of groups were done using the Mann-Whitney U test.
Results: The exercising patients showed increases in maximal oxygen uptake and upper body strength. This group also showed a greater percentage of CD4+CD69+ cells and a greater level of tritiated thymidine incorporation (DNA synthesis) when stimulated with ConA, PHA, and PWM at the end of the intervention. Plasma and mitogen-stimulated IL-6 and IFN-γ production were similar in both groups.
Conclusion: Exercise may improve immune function by increasing lymphocyte activation in patients with breast cancer following treatment.