Understanding the Mysterious M2 Macrophage through Activation Markers and Effector Mechanisms

Figure 1

Overview of the macrophage activation states. Macrophage activation is widely considered as a polarization towards M1 or M2 states. However, the M2 activation state involves heterogeneous and functionally distinct macrophages. The diagram represents the most prevalent examples of the M2 activation and lists the markers associated with the distinct activation phenotypes. The upstream signals are labeled in dotted frames. Abbreviations are defined in the text.