Inherited deficiency of the second component of complement. Rheumatic disease associations

Area of Science:

• Immunology
• Rheumatology
• Genetics

Background:

• The second component of complement (C2) plays a crucial role in the immune system.
• Deficiencies in C2 can be inherited and may be associated with autoimmune diseases.
• Previous research suggests a potential link between C2 deficiency and rheumatic conditions.

Purpose of the Study:

• To investigate the prevalence of homozygous and heterozygous C2 deficiency in patients with rheumatic diseases.
• To determine the association between C2 deficiency and specific rheumatic conditions like SLE and juvenile rheumatoid arthritis.
• To explore clinical and immunological characteristics of C2 deficient patients with SLE.

Main Methods:

• Immunochemical and functional assays were used to identify C2 deficiency.
• Prevalence was assessed in cohorts of patients with SLE, juvenile rheumatoid arthritis, and rheumatoid arthritis.
• Comparison with a control group of blood donors was performed.
• HLA typing and measurement of Properdin Factor B levels were conducted on C2 deficient individuals.

Main Results:

• A C2 homozygous deficient individual with SLE and 19 heterozygous deficient individuals were identified.
• The prevalence of C2 deficiency was significantly increased in patients with SLE and juvenile rheumatoid arthritis compared to controls.
• C2 deficient patients with SLE exhibited an earlier age of onset and lower antinuclear antibody levels.
• C2 deficient individuals showed significantly lower levels of Properdin Factor B.

Conclusions:

• Inherited C2 deficiency is significantly associated with an increased risk of developing SLE and juvenile rheumatoid arthritis.
• C2 deficiency may influence the clinical presentation of SLE.
• The findings support the role of the complement system in the pathogenesis of these autoimmune diseases.