How can the monitoring of complement parameters help to treat angioedema due to C1-inhibitor deficiency?

Abstract

Background: Acquired angioedema due to C1-inhibitor deficiency (C1-INH-AAE) is a rare disease that can be diagnosed by complement testing. It often accompanies lymphoproliferative underlying diseases. Methods: In the last 30 years, from the 3938 patients who were sent to the Angioedema Center with angioedema symptoms, we have diagnosed C1-INH-AAE in 19 cases, and monitored them regularly. The connections between the underlying disease, its treatment, the angioedema symptoms and complement parameters were investigated. Results: The 19 C1-INH-AAE patients were followed up for 6 years on average. Underlying disease was diagnosed in case of 15 patients. Most often lymphoma (6/19 patients) and monoclonal gammopathy of undetermined significance (6/19 patients) were found. There was no difference between the sexes regarding the complement parameters. Connection was found between the presence and activity of any underlying disease, the frequency of the angioedema attacks and the decreased level of proteins of the complement system. Angioedema specific long-term prophylaxis did not make an improvement in neither the frequency of the attacks nor in the complement parameters. Rituximab treatment reduced the number of attacks or completely made them disappear, and we experienced positive changes in complement parameters. Conclusion: Complement parameters supported the long-term efficacy of rituximab treatment for C1-INH-AAE. The change in complement parameters can predict the relapse of the underlying disease, and it is a good indicator for the prediction of angioedematous attacks. In case of C1-INH-AAE, it is significantly important to examine the patients for underlying disease, and to regularly follow up the patient’s complement parameters.