Autoimmune angioedema: a new role for autoantibody in disease pathogenesis

Angioedema may be due to hereditary forms of Cl-Inh deficiency, but recently an autoimmune form of angioedema has been described in which the mechanism is novel. While the peripheral blood monocytes of patients with autoimmune angioedema produce a normal, functionally active, 105 KD Cl-Inh in normal quantities, the Cl-Inh isolated from the patient's plasma exists in a dysfunctional lower molecular weight (96 KD) performance. Rather than bind and biologically inactivate the enzyme, a relatively common phenomenon in autoimmune disease, the autoimmune angioedema cleave the Cl-Inh molecule. The following sequence of events is proposed: structural and functionally normal Cl-Inh is synthesised and secreted, this secreted inhibitor is complexed by autoantibody and following enzyme interaction, denatured 96 KD Cl-Inh is proposed. This process depletes the pool of normal, functional Cl-Inh to critical levels and predisposes patients to episodes of oedema.