Acquired Angioedema

Angioedema

Angioedema without the presence of allergy continues to represent a medical paradox. This disorder is characterized by facial, laryngeal, genital or intra-abdominal swelling or swelling of the extremities. Much work has been undertaken to understand the genetics, pathogenesis, and clinical management of the angioedema. The angioedema is classified as hereditary and acquired types.

Acquired angioedema (AAE)

Acquired angioedema (AAE) is a rare condition characterized by edema. It can be immunologic, non-immunologic or idiopathic and is usually caused by the allergy and occurs together with other allergic symptoms and urticaria. This disorder was discovered in a patient who had angioedema and acquired C1-inhibitor (C1-INH) deficiency, which leads to the demonstration that an autoimmune mechanism may be the cause of the C1-INH deficiency.

Angioedema could be acquired and mainly in associate with lymphoproliferative disorders or occasionally with autoimmune, neoplastic, or infectious diseases, it could be classified into two subtypes, AAE-I and AAE-II.

1. AAE-I is linked to lymphomas, chronic lymphocytic leukemia, undefined lymphoproliferative diseases. Other disorders include multiple myeloma, myelofibrosis, and monoclonal gammopathies.
2. AAE-II is defined by the presence of an autoantibody recognizing the C1-INH. Epitope mapping report demonstrated that two potential epitopes in the intact C1-INH that binds to the C1-INH autoantibodies are peptide 2 (residue 438-449) and peptide 3 (residue 448-459).

Cause of AAE

C1-INH is a protease inhibitor whose function is to prevent the spontaneous hyperactivation of the complement system. Deficiency of C1-INH leads to the angioedema, hereditary angioedema (deficiency of C1-INH gene) and acquired angioedema (autoantibody directed against C1-INH).

Diagnosis of AAE

1. Testing C1-INH and C4
1. C1-INH and C4 are both normal→The deficiency of C1-INH is very unlikely.
2. C1-INH and C4 are both (C1-INH below 50% of normal on two separate determinations)→diagnosis of C1-INH deficiency are made.
3. Only C4 is low. The activity of C1-INH needs to be determined. If the activity of C1-INH is below 50% of normal on two separate determinations→diagnosis of C1-INH deficiency is made.
2. Differentiating hereditary and acquired deficiency

This test includes the determination of C1q which is reduced in 70% of the patients who are suffering from AAE but remains normal in hereditary angioedema patients.

3. Autoantibody Test

Autoantibodies directed against C1-INH should be detected for any angioedema-suspected patient. A solid-phase ELISA with simplicity and highly-sensitivity has been developed.

Symptom

1. Red skin welts
2. Swollen throat
3. Discolored skin patches
4. Vomiting
5. Abdominal pain
6. Diarrhea
7. Skin swelling
8. Gastrointestinal swelling
9. Respiratory tract swelling
10. Swelling (foot, lip, eyelid)

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• Hereditary Angioedema