C5 and acquired epidermolysis bullosa: These insights into C5a/C5aR1 pathophysiology also shape out current understanding of EBA pathogenesis: the binding of the autoantibodies to COL7 initiates blistering in EBA; one of the immediate subsequent events is the activation of complement, which in antibody transfer-induced EBA occurs within 24 h after anti-COL7 IgG injection (30).