Hypocomplementemia with low C1s-C1 inhibitor complex in systemic lupus erythematosus

Area of Science:

• Immunology
• Rheumatology
• Clinical Chemistry

Background:

• Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by immune system dysregulation.
• Complement system activation is implicated in SLE pathogenesis.
• Assessing complement activation markers is crucial for understanding disease activity.

Purpose of the Study:

• To investigate the correlation of C1s-C1 inhibitor complex levels with other complement components (C3, C4, C4a desarginine) and immune complexes in SLE patients.
• To evaluate the dynamic changes of C1s-C1 inhibitor complex in patients with hypocomplementemia over time.
• To determine the relationship between C1s-C1 inhibitor complex and clinical parameters in SLE.

Main Methods:

• Analysis of serum and plasma samples from 45 SLE patients.
• Measurement of C1s-C1 inhibitor complex, C3, C4, C4a desarginine, and staphylococcal protein A-bound immune complexes.
• Serial sampling over 6 months for 24 patients.
• Statistical correlation analysis.

Main Results:

• Significant correlations were found between C1s-C1 inhibitor complex and CH50, C4, and C4a desarginine.
• Complement activation, indicated by C1s-C1 inhibitor complex, was often transient in SLE patients with persistent hypocomplementemia.
• Staphylococcal protein A-bound immune complexes showed no correlation with complement assays.
• Abnormal C1s-C1 inhibitor complex levels were observed in pregnant SLE patients with normal complement levels.

Conclusions:

• Complement activation, assessed via C1s-C1 inhibitor complex, is frequently a transient event in SLE patients experiencing hypocomplementemia.
• C1s-C1 inhibitor complex serves as a valuable marker for monitoring complement activation dynamics in SLE.
• Further research is warranted to explore the clinical implications of transient complement activation in SLE management.