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C3-like activity in C3-deficient dog serum
Complement (Basel, Switzerland)
|January 1, 1987
Summary
Complement component 3 (C3) deficiency in Brittany spaniels leads to increased infections and kidney disease. Their serum contains a novel C3-like activity, potentially a new complement protein, that interacts with C5.
Area of Science:
- Immunology
- Complement System Biology
Background:
- A colony of Brittany spaniels exhibits a complete absence of the third component of complement (C3).
- This deficiency is inherited in an autosomal recessive manner.
- Affected dogs show increased susceptibility to infections and renal disease.
Purpose of the Study:
- To characterize the nature of the C3-like hemolytic activity present in C3-deficient dog serum.
- To investigate the properties and potential identity of this novel C3-like activity.
Main Methods:
- Hemolytic assays using EAC1,4,oxy2 cells.
- Sensitivity testing with heat, EDTA, methylamine, and D-76.
- Investigation of interactions with purified C5.
Main Results:
- C3-deficient dog serum retains approximately 10% of normal C3 hemolytic activity despite lacking detectable C3 antigen.
- This activity is heat-labile, EDTA-sensitive, and dose-dependently inhibited by methylamine and D-76.
- Lysis mediated by the deficient serum is inhibited by methylamine, but C5 addition boosts lysis more significantly in the absence of methylamine.
Conclusions:
- C3-deficient dog serum contains a methylamine-sensitive protein, distinct from C4, that interacts with C5.
- This protein may represent a newly discovered complement component.
- Further research is needed to fully identify and characterize this novel protein and its role in the complement cascade.