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Further studies on C9 deficiency
Insights
This study investigates a patient with C9 deficiency (C9D), finding their serum complement activity varies with buffer ionic strength. This indicates a defect in C9 synthesis impacting bactericidal activity.
Area of Science:
- Immunology
- Complement System Biology
Background:
- The complement system is crucial for innate and adaptive immunity.
- Terminal complement component C9 is essential for the formation of the membrane attack complex (MAC).
Observation:
- Serum complement activity (CH50) in the C9-deficient (C9D) patient varied significantly based on buffer ionic strength.
- Spontaneous lysis of EAC1-8 was identified as the cause of buffer-dependent CH50 variation in C9D serum.
- Serum bactericidal activity was low in C9D but enhanced by specific antibody addition.
Findings:
- The C9D patient exhibited a defect in C9 synthesis, as neither C9 inactivators nor anti-C9 antibodies were detected.
- The buffer-dependent CH50 variation is attributed to the influence of buffer conditions on spontaneous lysis of EAC1-8.
- Antibody plays a significant role in the serum's bactericidal activity, particularly in the context of C9 deficiency.
Implications:
- Understanding C9 deficiency aids in diagnosing and managing complement-related immune disorders.
- This research highlights the complex interplay between complement components, buffer conditions, and bactericidal function.
- Further investigation is needed to elucidate the mode of inheritance for C9 deficiency.
Abstract:
Further studies were carried out on the C9 deficiency (C9D). Her serum complement activity (CH50) was 15.7 units when assayed in high ionic strength buffer and 8.8 or less than 5.0 units when assayed in low ionic strength buffer containing glucose or sucrose, respectively. It was revealed that this buffer-dependent CH50 variation of C9D serum was due to the effect of the buffer on the spontaneous lysis of EAC1-8. The serum bactericidal activity of C9D was low, but the addition of specific antibody against bacteria increased the activity indicating an important role of antibody in the serum bactericidal activity. Neither C9 inactivator(s) nor antibody against C9 was detected in the serum, indicating that the case had a defect of C9 synthesis. However, the estimation of C9 levels in the sera of her family could not reveal the mode of inheritance of C9D.