FIGURE 1: Lysosome Fusion Maintains Phagosome Integrity during Fungal Infection. (A) Phagosomes expand their surface area by insertion of lysosomes. As C. albicans initiates filamentation inside the mature phagosome, luminal Ca²⁺ is released, leading to recruitment and insertion of lysosomes. This preserves phagosome integrity while restricting fungal growth. (B) The second wave of lysosome insertion can be inhibited by applying the Ca²⁺ chelator BAPTA. Preventing cytosolic Ca²⁺ transients during intraphagosomal growth leads to early phagosome rupture, NLRP3 inflammasome activation, and subsequent macrophage cell death. Actin polymerizes at the site where the hypha protrudes through the plasma membrane, possibly re-sealing the macrophage membrane and preventing leakage of cytosolic content.