**Abstract**

Infection with pathogenic microbes is a global threat. Macrophages play a fundamental role in promoting host resistance to deadly infections from pathogenic microbes by virtue of a well-orchestrated immune defense system. Phagocytosis and obliteration of invading pathogens by macrophages are an innate immune function that not only sustains immune homeostasis but also bolsters adaptive immune response through antigen processing and presentation. Wnt signaling, where Wnt, a secreted glycoprotein which interacts with Frizzled and ROR cell surface receptors to initiate cellular interactions, could be vital for the immune response executed and propagated by macrophages in both innate and adaptive immune responses. The goal of this chapter is to describe how Wnt signaling influences phagocytosis, autophagy, and transcriptional activation to enable the macrophage to exercise its immune response program to resist infection.

**Keywords:** macrophage, Wnt, phagocytosis, actin cytoskeleton, transcription, immunity
