Specimens collected at Auckland hospital:
Specimens must be delivered to LabPLUS within 60 mins of collection.
At the time of collection, place an "Urgent" label or Complement Pathways Activity sticker on the form. If only an urgent sticker is used, write clearly below it " Complement Pathways Activity " . Contact Ichem on 09 307 49 49 ext. 22113 to inform the laboratory once the sample has been collected.
Microcollects are not suitable for pathway activity assays due to contamination with tissue fluids.
It is crucial the sample is clotted at room temperature for 60-90 mins before spinning and frozen immediately after spinning at -20 0 C
Specimen Collected at offsite and sent to Labplus:
Please allow specimen to clot at room temperature for between 60 and 90 minutes before spinning.
Please freeze specimen at -20 0 C
Place " Urgent " sticker on the form.
Ensure the "
Urgent
"
label is visible when form is placed in the biohazard bag. Transport frozen.
Sample could arrive via Lamson and/or via the Front Counter
Please note: A dedicated tube (ie. only requiring pathway activity assays) must be sent for this assay.
.
| Pathway | Reference interval, % | Uncertainty if measurement, % |
|---|---|---|
| Lectin Pathway | 0 - 125 | 30% |
| Alternative Pathway | 30 - 113 | 10% |
| Classical Pathway | 69 - 129 | 22% |
(all age ranges, either sex)
.
This test is an enzyme linked immunosorbent assay (ELISA) that detects complement activation using the Wielisa Total Complement Screen COMPL 300 ELISA.
Complement pathways (classical, alternative and the newly discovered lectin pathway) are measured by an ELISA that activates each specific pathway. The activity is detected by a labelled monoclonal antibody to C5-C9 complex (MAC). The main use of complement pathways is to detect either primary or secondary complement deficiency. Homozygous deficiency of an individual component will result in an absence of the affected pathway. In secondary deficiency, complement pathways can be used to monitor disease activity.
Many persons who are in otherwise good health have absent lectin pathway responses. The clinical implications of this are unknown at present.
Background
Complement comprises a group of protease precursors and regulating proteins produced by the liver and present in normal serum. When activated they act as mediators of inflammation and immune effectors. Foreign surfaces, e.g. bacterial cell walls (alternative pathway), or antibody bound to antigen (classical pathway) causes sequential activation in a cascade effect. The central reaction involves the deposition of large amounts of C3b on pathogens and immune complexes, which acts as an opsonin facilitating phagocytosis. By products of this reaction, anaphylotoxins, act as powerful mediators of inflammation. The terminal complement components can cause direct damage to targets by formation of the membrane attack complex (MAC).
Classical pathway
Ag+Ab->C1->C4->C2->C3->C3b +
anaphylotoxins
->C5->C6->C7->C8->C9 (
MAC
)
Alternative pathway
Bacterial wall+Factor B->C3->C3b + anaphylotoxins ->C5->C6->C7->C8->C9 ( MAC )
Lectin pathway
Microbial carbohydrate + mannan binding lectin ->MASP->C1->C4->C2->C3b + anaphylotoxins ->C5->C6->C7->C8->C9( MAC )
The main functions of the complement cascade are in defence against infections, predominantly bacterial, and in clearance of immune complexes. Complement deficiencies can lead to poor immune complex clearance and lupus-like syndromes (classical pathway deficiencies (C1,2 and 4) are rare), severe pyogenic bacterial sepsis (alternative pathway and C3 deficiencies) or systemic Neisserial infections (terminal complement components and MAC). These can be caused by inherited deficiencies or functional abnormalities, depletion due to chronic activation or abnormalities of regulatory proteins. Deficiency or functional impairment of the classical pathway regulatory component C1 inhibitor leads to inappropriate production of anaphylotoxins and hereditary angio-oedema.
The production of complement components can be increased by systemic inflammation as part of the acute phase response, and reduced by hepatic impairment. Reduction of individual components commonly reflects chronic activation of that pathway.
- M.R. Daha etal, A novel ELISA-based assay for the measurement of the three activation pathways of the complement system, Clinical Laboratory, 2004, 28 (17-18)
- Wielisa -kit insert, Total Complement System screen Classical, MBL, Alternative Pathways, version: 040624
For further information contact the laboratory (09) 307 4949 ext 22000 or:
Associate Professor Rohan Ameratunga , Immunopathologist: Locator 93-5724
Or the LabPLUS Immunology Team
Blood samples must be allowed to clot at room temperature (20 - 25 o C) for 60-90 minutes before being spun. Samples must then be separated immediately and frozen at -70 o C or lower. Samples not meeting these requirements may not be processed.