PDF iconKidney Disease Testing Requisition Form (Effective beginning January 3, 2017)

The Clinical Diagnostics Service of the Molecular Otolaryngology & Renal Research Laboratories is a CLIA-approved, Joint Commission-accredited diagnostic laboratory.

Hemolytic Assay - Sheep Erythrocyte Lysis Assay
Sheep erythrocytes are non-activating surfaces. This assay measures complement-mediated lysis of sheep erythrocytes secondary to activation of the alternative pathway (AP). Lysis can be seen in the serum of patients with aHUS and DDD.

Indications for screening
Screening is appropriate for patients with aHUS and biopsy-proven DDD.

MORL screening methodology
Sheep erythrocytes are used as index cells in this assay. Sheep erythrocytes generally act as non-activators of complement-mediated lysis in human serum. A small number of C3b molecules spontaneously generated through AP tick-over are deposited on the surface of sheep erythrocytes. In normal human serum, factor H binds to C3b molecules through its N-terminal domains and to sheep erythrocytes through its C-terminal domains. These interactions result in efficient protection of sheep erythrocytes against complement and no lysis is observed (Dragon-Durey et al., 2005, Józsi et al., 2007).

Abnormal hemolytic activity may be seen when serum from patients with aHUS is used in this assay if these patients carry either genetic mutations or acquired risk factors for aHUS such as FH autoantibodies. While abnormal hemolytic activity may also be seen with serum from patients with DDD if these patients carry either genetic mutations or acquired factors for DDD such as C3 nephritic factors; hemolysis will be absent when consumption of AP proteins has been extensive and only a small amount of AP proteins remain in the serum.

Sensitivity
Unknown

Turnaround time
Turnaround time is ~ 4 weeks

Sample Required
1 ml frozen serum (see testing requisition for specimen handling).

Cost & CPT Codes
See the MORL testing menu

Web sites

KIDNEEDS (not-for-profit foundation dedicated to the cure of DDD)
http://www.healthcare.uiowa.edu/kidneeds/

Foundation for Children with Atypical HUS
http://www.atypicalhus.50megs.com/index.html

References

Dragon-Durey, M. et al.: Anti-Factor H autoantibodies associated with atypical hemolytic uremic syndrome. J Am Soc Nephrol. 2005 Feb;16(2):555-63.
PubMed ID: 15590760

Józsi, M. et al.: Anti factor H autoantibodies block C-terminal recognition function of factor H in hemolytic uremic syndrome. Blood. 2007 Sep 1;110(5):1516-8.
PubMed ID: 17495132