To better understand the potential impact of the gene expression network structure on the dynamics of immune-senescence and defects of cell functions during aging, we investigated network structures in both young and old individuals. We analyzed the gene co-expression networks (GCNs) derived from an aging signature of 130 immune-related genes obtained from CD3+ T-cell splenocytes extracted from FVB/N, C57BL/6N, and BALB/c mice at ages 2 and 22-24 months. The network structure for the two different mouse age-groups was derived and subsequently analyzed. Analysis of network hubs using clustering coefficients, degree, betweenness, eigenvector, and closeness centralities, as well as local, indirect, and total influence measures, demonstrated changes in gene behavior and network control between the two age groups. Our quantification shows that the young, 2-month old mouse network is more organized than the 22-24-month, old mouse network, while the network structure of the older mouse GCN appears to be far more complicated but far more dispersed. Changes in network structure between the old and young mice suggest deterioration in transcription regulation with age in peripheral T-cells, particularly within the TCR signaling pathway, and potential compensatory mechanisms in older T-cells to overcome loss to regular function resulting from transcriptional irregularity. These results demonstrate the need for more research into gene co-expression in peripheral T-cells in order to better understand both network irregularities and the phenotypic dysfunction observed in older individuals.