Advanced Diagnostic Laboratories

C4a Level By RIA

Test Code

C4AR

Description

The complement system is part of our innate immune response. It is vital to our defense against invasive microorganisms. Complement activation can occur through the classical, lectin and alternative pathway, which then converge to a common terminal pathway. Activation of the complement pathway(s) results in the generation of pharmacologically active peptides, also known as complement split products, and referred to as anaphylatoxins (C4a, C3a, C5a) which protect us from invasive microorganisms by enhancing inflammation, facilitating the clearance of immune complexes and apoptotic cells, enhancing cellular and antibody immune responses and altering vascular permeability, as well as smooth muscle contractility.

The anaphylatoxin C4a can be elevated above normal levels in many conditions associated with inflammation, including chronic fatigue syndrome, multiple sclerosis, immune complex diseases such as antiphospholipid syndrome and autoimmune conditions such as lupus. C4a is also an early marker of acute Lyme disease.

Collect

Plasma from a lavender top (K2 - EDTA) tube is the only acceptable sample type. Mix sample thoroughly. Keep tubes cold on wet ice or with a cold pack after collection.

Specimen Preparation

Within 30 minutes of venipuncture, centrifuge at 4°C. Transfer the cell-free plasma to a clean tube and immediately freeze on dry ice or at -70°C or below.
Preferred volume: 1 mL

Ambient temperature for centrifuging is acceptable provided that the time between collection, spinning and decanting to the freezer, is minimized (approximately 30 minutes).

Patient Prep

Within 30 minutes of venipuncture, centrifuge at 4°C. Transfer the cell-free plasma to a clean tube and immediately freeze on dry ice or at -60°C or below in an ultra-low freezer.

Preferred volume: 1 mL

Ambient temperature for centrifuging is acceptable provided that the time between collection, spinning and decanting to the freezer, is minimized (approximately 30 minutes).

Pediatric Collection

Minimum volume: 500 µL plasma, frozen.

Unacceptable Conditions

Thawed specimen or specimens stored at room temperature prior to shipment.

Storage Transport Temp

Send frozen plasma Priority Overnight via FedEx and in a well-insulated container on dry ice.

Stability

Frozen at -70°C: 2 year

Notes

Additional testing time may be needed for less than perfect samples or confirmatory testing/reflex testing.

Performed

Monday - Friday

Methodology

Radioimmunoassay (RIA).

The I125 C4a Des Arg RIA system provides direct quantitative measurement of C4a in human plasma. This radioimmunoassay (RIA) method includes a pre-processing step to remove full length C4 from the sample to eliminate the potential cross-reactivity with measurement of C4a that is often associated with traditional sandwich ELISA methods.

Reported

7 - 10 business days.

Department

Complement Lab

Synonyms

RadioImmunoassay (C4a Level), C4ades Arg Level, C4ades Arg Level (C4a Level), C4 (C4a Level), C4 anaphylatoxin (C4a Level), C4a anaphylatoxin, Complement (C4a Level), C4AL

Related Tests

C3AR, C4