These observations likely result from the finding that significant production of IL-17 during endotoxemia is from macrophages (Bosmann et al., 2012), and C5a differentially affects macrophage-derived IL-17 and IL-17F as described above (see Modulation of IL-17 in Acquired Immunity by C5a). The gene discussed is C5AR1; the disease is serum lipopolysaccharide activity.