Test Details
Methodology
Enzyme immunoassay (EIA)
Result Turnaround Time
4 - 8 days
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Use
For the measurement of C3d-bound circulating immune complexes (CIC) present in human plasma or serum.
Limitations
False-positives occur when antilymphocyte antibodies are present. This assay does not detect noncomplement fixing CIC. Occasionally, positive specimens may not confirm. Nonconfirming specimens may be due (among other reasons) to contaminated or heat-inactivated specimens or specimens containing human IgG antibodies that bind to mouse IgG. Such specimens, however, are not necessarily negative for CIC. The material causing the apparent false-positive result may mask concomitantly occurring CIC that, if they were present alone, would otherwise yield a confirmable positive CIC result.
Custom Additional Information
The importance of circulating immune complexes, and their relationship to various diseases, has been the subject of study for many years. Formation of immune complexes is a protective and usually benign process of a normally functioning immune system. CIC are removed from circulation by a number of complex biochemical, enzymatic, and cellular processes. Key to all of these, however, is the complement system.
In certain disease states, immune complexes may initiate complement-mediated damage of various organs and tissues. This activation of complement may begin a series of potentially destructive events, including cell lysis, the production of anaphylatoxins, leukocyte stimulation, and activation of macrophages. Major tissue damage can also occur with IC fix to cell membranes as in some cases of glomerulonephritis.
More than 40 assays have been developed to measure CICs, many of these require multiple complex steps and sophisticated equipment. Since the characteristics of CIC vary widely, none of these assays has been accepted as standard. In fact, in a comprehensive study, the WHO determined that no single method was appropriate to measure CIC in all disease states and that a combination of two different methods and techniques be used.
Specimen Requirements
Specimen
Serum or plasma, frozen
Volume
1 mL
Minimum Volume
0.1 mL
Container
Red-top tube or gel-barrier tube; lavender-top (EDTA) tube is also acceptable.
Collection Instructions
Transfer specimen to a plastic transport tube before freezing. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.
Reference Range
• Normal: <15.1 μg Eq/mL
• Equivocal: 15.1−19.9 μg Eq/mL
• Positive: >19.9 μg Eq/mL
Storage Instructions
Freeze at -70°C or store on dry ice within six hours of collection. Specimen is stable for 14 days if stored at -70°C. Storage of specimens at -20°C will yield erroneous results.
Causes for Rejection
Specimen not received frozen on dry ice
LOINC® Map
| Order Code | Order Code Name | Order Loinc | Result Code | Result Code Name | UofM | Result LOINC |
|---|---|---|---|---|---|---|
| 123014 | C3d Immune Complexes | 123015 | C3d Immune Complexes | ug Eq/mL | 10864-7 | |
| Order Code | 123014 | |||||
| Order Code Name | C3d Immune Complexes | |||||
| Order Loinc | ||||||
| Result Code | 123015 | |||||
| Result Code Name | C3d Immune Complexes | |||||
| UofM | ug Eq/mL | |||||
| Result LOINC | 10864-7 |