Related Experiment Videos
Measurement of complement activation products in patients with chronic rheumatic diseases
G Auda1, E R Holme, J E Davidson
1University Department of Pathology, Western Infirmary, Glasgow, UK.
Insights
Complement activation products are elevated in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) patients. These levels correlate with rheumatoid factor (RF) in RA patients, indicating their role in rheumatic diseases.
Area of Science:
- Immunology
- Rheumatology
- Biochemistry
Background:
- The complement system plays a crucial role in immune responses and inflammation.
- Aberrant complement activation is implicated in the pathogenesis of autoimmune and rheumatic diseases.
- Specific complement activation products can serve as biomarkers for disease activity.
Purpose of the Study:
- To measure plasma levels of complement activation products in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE).
- To investigate the correlation between these complement activation products and rheumatoid factor (RF) in seropositive RA patients.
- To assess the influence of IgM-RF on the detection of complement activation products using ELISA.
Main Methods:
- Enzyme-linked immunosorbent assay (ELISA) was used to measure complement activation products C1s:C1-inh, C3bP, and C5b-9 in plasma samples.
- Plasma samples were collected from healthy individuals, RA patients, and SLE patients.
- Correlations were analyzed between complement activation products and RF isotypes (IgM-RF, IgG-RF, IgA-RF) in seropositive RA patients.
Main Results:
- Significantly elevated levels of C1s:C1-inh, C3bP, and C5b-9 were observed in RA and SLE patients compared to healthy controls (P < 0.0001).
- In seropositive RA patients, significant correlations were found between the levels of the three complement activation complexes and IgM-RF, IgG-RF, and IgA-RF.
- IgM-RF did not interfere with the ELISA assays used for complement activation product measurement.
Conclusions:
- Elevated plasma levels of complement activation products are detectable in patients with rheumatic diseases like RA and SLE.
- Plasma levels of these complement activation products are related to rheumatoid factor levels in seropositive RA patients.
- The solid-phase ELISA procedures used are not influenced by IgM-RF, ensuring reliable measurement of complement activation products.
Abstract:
Measurement of the complement activation products C1s:C1-inh, C3bP and C5b-9 by ELISA in plasma samples from normals, rheumatoid arthritis (RA) and systemic lupus erythematosis (SLE) patients showed significantly elevated levels in the two patient groups (P less than 0.0001 for C1s:C1-inh, C3bP and C5b-9) compared to normals. In seropositive RA patients there were significant correlations between the levels of the three complement activation complexes and IgM-RF, IgG-RF and IgA-RF. However, IgM-RF did not interfere with any of the ELISA systems. Mean levels of C1s:C1-inh, C3bP and C5b-9 were the same in paired plasma and synovial fluids; however, C3bP levels in the paired samples did not correlate with one another by rank. Our conclusions are that: (a) elevated plasma levels of these complement activation products are detectable in rheumatic diseases; (b) plasma levels of these complement activation products are related to Rheumatoid factor (RF) levels in seropositive RA patients; and (c) IgM-RF does not influence these solid-phase ELISA procedures.