The Clinical Diagnostics Service of the Molecular Otolaryngology & Renal Research Laboratories is a CLIA-approved, Joint Commission-accredited diagnostic laboratory.
Properdin Level Assay
Properdin is a single chain plasma glycoprotein (MW: 58 kDa) mainly secreted by white blood cells including monocytes, lymphocytes and neutrophils. It is present in the circulation as a mixture of head-to-tail dimers, trimers and tetramers, with a preponderance of trimers.
Properdin is a positive regulator of the alternative pathway (AP) of complement. In addition to initiating the AP, properdin binds to and stabilizes the C3 convertase, C3bBb increasing its half-life approximately 10 fold. The increased half-life enhances amplification of C3bBb formation, which eventually leads to the formation of the C5 convertase, C3bBbC3b, and initiation of the terminal pathway of complement.
The common pathophysiological basis of both Dense Deposit Disease (DDD) and C3 Glomerulonephritis (C3GN) is dysregulation of the AP. Consumption of AP complement components is dependent on the degree of dysregulation of the C3 and C5 convertases. While properdin plasma levels are often reduced in both DDD and C3GN, properdin levels are generally lower in C3GN as compared to DDD (p<0.01) (see Zhang et al. Defining the complement biomarker profile of C3 glomerulopathy, CJASN 2014).
Indications for screening
Screening is appropriate in patients with complement-mediated renal diseases.
MORL screening methodology
Enzyme Linked Immuno-Sorbent Assay (ELISA)
Turnaround time is ~2 weeks
1 ml frozen EDTA plasma (see testing requisition for specimen handling).
Cost & CPT Codes
See the MORL testing menu