C1Q BINDING ASSAY
- Code
- 000.0000
- Name
- C1Q BINDING ASSAY
- Category
- None
- Department
- Send-Out
- Start Date
- Expiration Date
- Synonyms
- Circulating Immune Complex Detection by C1q Binding
- CPT Codes
- 86332
- Site
- SBMF
- Reference Test
- 44042
Specimen Information
- Type
Red, Plain
- Volume
1.0 ml
- Transport Info
Centrifuge and immediately transfer serum to separate plastic tube
FrozenCRITICAL FROZEN – Separate samples must be submitted when multiple tests are ordered
- Fasting Required?
- False
- Patient Instructions
- Reference Range
C1Q Binding Assay
Less than 4 µgE/mL is considered negative for circulating complement binding immune complexes- Methodology
Enzyme-Linked Immunosorbent Assay
Clinical Significance
A variety of diseases are associated with circulating immune complexes (CIC). CICs are formed by the interaction of antibodies with specific antigen. This normal process of the immune response results in the rapid clearance of CICs by the reticuloendothelial system. However, in some cases there is deposition of CICs in tissues with associated inflammatory-mediated damage. Elevated CICs have been detected in a variety of autoimmune diseases (e.g., systemic lupus erythematosus [SLE], rheumatoid arthritis [RA], etc.), certain cases of glomerulonephritis, infectious diseases (e.g., Lyme disease, chronic HBV infection, HIV infection, endocarditis, etc.), and some malignancies. Some authors believe that immune complex determinations may be useful in monitoring disease activity in certain autoimmune disorders, particularly RA and SLE. A positive CIC assay, however, does not necessarily implicate immune complexes in disease pathogenesis, nor does it necessarily correlate well with disease activity. Circulating immune complexes may be found without any evident pathology and positive results do not necessarily implicate the immune complex in a disease process. There are two general categories of CICs: antigen-specific (e.g., to HBsAg) and antigen-nonspecific. In most clinical circumstances the nature of the specific antigen is unknown. Therefore, most assays are designed to detect antigen-nonspecific CICs. These include Raji cell, C1q binding, conglutinin, and anti-C3 assays. C1q is a normal component of the C1 factor molecular complex and possesses multiple recognition sites for the heavy chain of the immunoglobulin (Ig) molecules. Assays for CICs target C1q and its ability to bind Ig. In general, however, C1q assays are the least sensitive and specific for CICs.