Before we proceeded to investigate an alternative mechanism cleaving C5 to generate C5a other than complement cascades in rat IA lesions, we verified a positive control of the complement cascade activation in immunohistochemistry using the tissue section from anti-Thy-1.1-induced glomerulonephritis model, which is a representative disease caused by complement activation (Fig. 5B). Here, C5AR1 is linked to glomerulonephritis.