IFNγ secreted at early stages of infection enhances antigen presentation by antigen-presenting cells (APCs), such as macrophages and dendritic cells, by inducing MHC expression (Amaldi et al., 1989; Steimle et al., 1994; Xaus et al., 2000; Schroder et al., 2004). The gene discussed is IFNG; the disease is infection.