Low serum haemolytic function of the fourth complement component (C4) in insulin dependent diabetes

Area of Science:

• Immunology
• Endocrinology
• Genetics

Background:

• Low serum concentrations of the fourth component of complement (C4) are observed in insulin-dependent diabetes mellitus (IDDM).
• These low C4 levels may play a role in the disease's etiology.
• The functional capacity of C4 in IDDM requires further investigation.

Purpose of the Study:

• To investigate whether the function of C4 is impaired in individuals with IDDM.
• To compare C4 function and concentration in IDDM patients, non-IDDM patients, and healthy controls.
• To explore the role of C4 in the genetic predisposition to IDDM using discordant monozygotic twins.

Main Methods:

• Radial immune hemolytic assay was used to measure C4 hemolytic activity (function).
• Laser nephelometry was employed to determine C4 concentration.
• Study included 34 IDDM patients, 15 non-IDDM patients, 20 healthy subjects, and 12 discordant monozygotic twin pairs.

Main Results:

• Both C4 function and concentration were significantly lower in IDDM patients compared to non-IDDM patients and healthy controls.
• C4 function and concentration were also reduced in both diabetic and non-diabetic twins compared to controls.
• A strong correlation was observed between C4 function and concentration in both diabetic and non-diabetic twins.

Conclusions:

• Defects in both C4 function and concentration are evident in insulin-dependent diabetes.
• The presence of these defects in non-diabetic co-twins suggests a potential genetic predisposition to IDDM.
• C4 deficiency may represent a heritable risk factor for developing insulin-dependent diabetes.