Breast Cancer Survivors Exhibit Normal T-Cell Mobilization But Divergent Intracellular Cytokine Expression With Acute Exercise

Breast cancer (BC) treatment decreases circulating T-cells, with delayed recovery being associated with higher metastatic rates. BC survivors (BCS) may have attenuated responses to acute exercise, with reduced cellular mobilization and limited inclusion of functional markers. PURPOSE: To investigate the effects of acute aerobic exercise in BCS and healthy older women (CON) on T-cell counts, frequency, and intracellular cytokine expression. METHODS: Age-matched BCS (n = 13, age = 57 ± 9) and CON (n = 13, age = 58 ± 7) performed 45 min of intermittent cycling at 60% peak power output. Blood samples were obtained at rest, 0 h, and 1 h post-exercise. T-cell counts, frequency, and intracellular cytokine expression were determined with flow cytometry. p < 0.05 and p < 0.1 were used for main effects and interactions. RESULTS: Overall, CON had higher CD3 (+481 cells, 95% CI [188, 773], p = 0.004) and CD4 (+376 cells, [135, 618], p = 0.005) counts. At 0 h, cell counts increased for CD3 (+387 cells [242, 492]), CD4 (+199 cells [101, 297]) and CD8 (+76 cells [46, 105], all p < 0.001). The CD4 frequency interaction was significant (p = 0.047). Both groups decreased similarly at 0 h (-4.4% [-7.4, -1.3], p = 0.007) while CON increased by 4.5% ([0.1, 9.0], p = 0.044) at 1 h while BCS remained suppressed. The CD8 frequency interaction was also significant (p < 0.001). CON was unchanged throughout while BCS increased by 4.9% ([2.0, 7.7], p = 0.001) at 1 h. The interaction for CD4 TNFα was significant (p = 0.006), where CON increased at 1 h (+10.8%, [3.5, 18.2], p = 0.005) while BCS tended to decrease (-6.7%, [-14.1, 0.8], p = 0.079). Similar patterns were seen in CD8 TNFα frequency, although the relationship was not as strong. The CD4 IFNγ frequency interaction was significant (p = 0.081), with CON increasing at 0 h (+5.6. [0.1, 11.0], p = 0.045) and remaining constant, while BCS revealed a non-significant decrease at 1 h (-3.2. [-8.5, 2.1], p = 0.233). CONCLUSIONS: Independent of exercise, BCS had lower CD3 and CD4 T-cell counts compared to CON. Following exercise, CD4 frequency demonstrated the expected decline but with a slower return to baseline levels in BCS. Intracellular cytokine responses to acute exercise appear to be divergent, with lower levels in BCS that may indicate reduced functional capacity for T-cell pathogenic responses and infection control. Breast Cancer Foundation of NY