Macrophage Polarization Mini Review

In the 1990s it was discovered that the cytokine interleukin (IL)-4 induced different effects on macrophage gene expression compared to that of interferon (IFN)-gamma and lipopolysaccharide (LPS). In contrast to the classical activation of macrophages by IFN-gamma (Nathan CF et al. 1983), the macrophage gene expression induced by IL-4 was described as “alternative activation” (Stein M et al. 1992, Martinez FO and Gordon S 2014).