The immune system is a dynamic network that processes information across multiple biological scales, from molecular recognition of antigens to systemic coordination with the neuroimmune axis and microbiota. At the molecular level, pathways such as NF-κB and JAK-STAT regulate gene expression, integrating signals from pathogens and the organism itself while balancing activation through feedback loops. Cellular and tissue-level dynamics are exemplified by germinal centers, where B-cell hypermutation and clonal selection refine the humoral response, and by immunological synapses that regulate T-cell activation and fate. Systemically, the vagus nerve mediates neuroimmune interactions, while the microbiota co-evolves with the immune system, enhancing its plasticity and robustness. These processes embody antifragility, allowing the immune system to strengthen and expand its capabilities with each challenge. By understanding these multiscale processes, novel strategies emerge for precision medicine, including the modulation of the vagus nerve and microbiota, offering personalized approaches to treat infectious, autoimmune, and chronic diseases.