The most significant defense against fungal infections is cellular immunity.

• A. The Most Significant Defense Against Fungal Infections Is Humoral Immunity.
• B. The Most Significant Defense Against Fungal Infections Is Cellular Immunity.
• C. Phagocytosis Is The Only Essential Defense Against Fungal Infections.
• D. Complement Activation Overwhelmingly Controls Fungal Infections.

Answer: (B)

Cell-mediated immunity is the most important line of defense against fungal infections. T cells, especially TH1 cells, produce IFN-γ that activates macrophages. These activated macrophages kill intracellular fungi and contain infection, which is crucial because many fungi can survive inside host cells or form lesions that require a strong cellular response to clear. Antibodies and complement help in some situations, such as opsonizing extracellular forms, but they often can’t reach or eliminate fungi living inside cells, so they aren’t the primary protective force. Phagocytosis matters, but without the activating signals from T cells, ingested fungi may persist. Thus the cellular immune response, with macrophage activation and granuloma formation driven by T cells, is the key defender against fungal pathogens.