FCN2 and infection: We also found that ficolin-2 enhanced macrophage opsonization with H37Rv (Figure 3B), which was primarily due to uptake because the process was inhibited by cytochalasin B. We speculated that ficolin-2 inhibited Mtb H37Rv infection of A549 alveolar epithelial cells and stimulated opsonization of macrophages, perhaps through the two different domains of ficolin-2 (i.e., the FBG domain and the collagen-like domain).