Table 2 The key findings from the analysis conducted

Antibody Titers

Significant increase in antibody levels at T1, followed by a decrease at T2, except for anti-Bx-85cB in the young group (no significance at T2). Older adults showed higher baseline titers (not significant) but lower titers than young adults at T1 and T2 (p-values: T1 = 0.0055, T2 = 0.0043).

T Cell Immunophenotype

Age-related decrease in CD4 + and CD8 + naïve T cells. CD8 + naïve T cells showed significant reduction at T1 in older vs. young adults (p = 0.004). CD8 + TEM were higher in older adults at T1 (p = 0.039). CD8 + TEMRA decreased in older adults at T1, with a significant T0 difference between young and old (p = 0.0438).

PBMCs stimulation with PepTivator^® Influenza

OLE and OLE + BIRB 796 reduced CD4+/CD8 + TNF-α + T cells in older adults, with variable trends in young individuals. CD8 + IFN-γ + T cells were higher in older adults across conditions. OLE + BIRB 796 synergistically reduced CD4 + IFN-γ + T cells in older adults at T1. IL-10 trends varied by age and condition, without statistical significance and a clear trend.

ROS/RNS Analysis

Older adults showed lower ROS/RNS levels compared to young individuals across all conditions. OLE and OLE + BIRB 796 significantly reduced ROS/RNS levels in both age groups at T0 and T1 (e.g., T0 older adults: PEPs vs. OLE, p < 0.0001). No significant differences were found between T0 and T1 within groups.