• Cellular and tissue-level immunity emerges as the central paradigm, linking neutrophils and leukocytes to lymphoid tissues and tissue-specific immune responses across species, as shown by inflammatory, lymphatic, and phagocyte studies. Key sources include neutrophil behavior (1904), lymph node architecture (1902), tissue immunity (1905), and phagocyte dynamics (1908). [3], [6], [7], [8], [9], [20].

• Serum therapy and immunotherapy establish a therapeutic paradigm, with early serum-based interventions and immunological treatment concepts guiding infectious and autoimmune disease management. Exemplars include Abrin-immunotherapy (1901), infection-immunity-serum therapy (1906), ocular serum therapy (1902), and TB-immunity perspectives (1910). [1], [4], [11], [14].

• Infection control, public health, and disease-specific immunity shape practical strategies for tuberculosis and poliomyelitis, and immune pathology in infections, reflecting bench-to-clinic translation. [4], [14], [18], [19].

• Lymphatic system and lymphoid architecture underpin immune function, with studies on lymph nodes, lymphatics, and leukocyte trafficking guiding systemic immunity concepts. [7], [9], [13], [15].

• Molecular dimensions and nucleic-acid studies signal an incipient molecular era in immunology, providing quantitative tools and mechanistic insight into immune processes. [5], [16].