M1 polarization occurs in the presence of interferon (IFN)-γ, granulocyte-macrophage colony-stimulating factor (GM-CSF), and lipopolysaccharide (LPS) via signal transducer and activator of transcription 1 (STAT1), interferon regulatory factor 5 (IRF5), or nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), whereas fungal and helminth infections, interleukin (IL)-4, IL-10, IL-13, and tumor growth factor (TGF)-β skew macrophages toward M2 via STAT6, peroxisome proliferator-activated receptor γ (PPARγ), PPARδ, or Jumonji domain-containing protein D3 [8,13]. The gene discussed is IRF5; the disease is helminthiasis.