Complement and protease inhibitors in the mucocutaneous lymph node syndrome

Area of Science:

• Immunology
• Pediatrics
• Biochemistry

Background:

• Mucocutaneous Lymph Node Syndrome (MCLS) is an acute febrile vasculitis affecting children.
• The role of complement system and protease inhibitors in MCLS pathogenesis is not fully understood.

Purpose of the Study:

• To investigate the levels of complement components and protease inhibitors during the acute phase of MCLS.
• To correlate these levels with disease severity and patient outcomes.

Main Methods:

• Serum samples were collected during the acute phase and convalescence from Japanese and European children with MCLS.
• Measurements included total hemolytic activity of serum (CH50), complement components (C3, C4), and protease inhibitors (alpha 1AT, alpha 1X, AT III, alpha 2M, I-alpha-I).
• Coronary risk scores were used to assess disease severity.

Main Results:

• Low CH50 levels were observed in 10 out of 11 high-risk children, associated with severe outcomes like coronary aneurysms.
• Elevated C1 inhibitor, alpha 1-antitrypsin (alpha 1AT), and alpha 1-antichymotrypsin (alpha 1X) were frequent in acute MCLS.
• Decreased concentrations of antithrombin III (AT III), alpha 2 macroglobulin (alpha 2M), and inter-alpha-inhibitor (I-alpha-I) were associated with more severe disease courses.
• Concentrations normalized in a follow-up group evaluated 5 weeks to 6 months post-illness.

Conclusions:

• Consumption of complement and protease inhibitors occurs during the acute phase of MCLS.
• CH50 determination is a valuable tool for early identification of high-risk patients.
• Transient deficiencies in inflammation control factors may contribute to severe vascular lesions in MCLS.