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[Hereditary deficiency in complement C7 and platelet aggregation disorders associated with rheumatoid arthritis. One
Insights
Complete deficiency of the 7th complement component (C7) was found in a rheumatoid arthritis patient. This hereditary C7 deficiency impacted serum bactericidal activity and platelet aggregation, suggesting a link between complement function and autoimmune disease.
Area of Science:
- Immunology
- Genetics
- Rheumatology
Background:
- Rheumatoid arthritis (RA) is a chronic autoimmune disease.
- Complement system deficiencies can increase susceptibility to infections and autoimmune conditions.
- The 7th complement component (C7) plays a role in the membrane attack complex formation.
Observation:
- A patient with rheumatoid arthritis presented with a complete deficiency in the 7th component of the complement (C7).
- Family studies confirmed the deficiency as an autosomal codominant hereditary trait, independent of the HLA system.
- Serum analysis revealed preserved opsonizing and chemotactic activities but absent bactericidal properties.
Findings:
- The C7 deficiency was hereditary and autosomal, unrelated to the HLA system.
- Key complement-dependent serum functions, including bactericidal activity, were impaired.
- Platelet aggregation disorders were observed in the presence of thrombin and corrected by C7 addition.
Implications:
- The co-occurrence of C7 deficiency and rheumatoid arthritis may not be coincidental.
- A shared genetic abnormality or recurrent infections could link C7 deficiency and autoimmune dysregulation.
- Understanding C7's role may offer new insights into RA pathogenesis and complement-related disorders.
Abstract:
In a patient suffering from rheumatoid arthritis thorough investigations led to the discovery of complete deficiency in the 7th component of the complement. A study of the patient's family tree confirmed the hereditary, codominant autosomal character of the deficiency, unrelated to the HLA system. The complement-dependent serum functions were investigated: the opsonizing and chemotactic activities were preserved, but bactericidal properties were lacking. Coagulation studies showed disorders in platelet aggregation in the presence of thrombin, and these were corrected by the addition of C7. The association of a dysimmune disease with C7 deficiency is probably not fortuitous; it might result from a common gene abnormality or, in some cases, from repeated infections.