Collagen-Binding Assay Assessed for Bleeding Disorder

Scientists at Westmead Hospital, (Westmead, NSW, Australia) tested plasma samples from 52 type I and 49 type 2 VWD patients and 242 plasma samples from apparently healthy individuals to determine the normal reference interval. Precision analysis was performed using three reference plasma samples. A collagen-binding enzyme-linked immunosorbent assay (ELISA) was performed and the absorbance was read at 450 nm with a 650 nm reference on a Versamax plate reader (Molecular Devices, Sunnyvale, CA, USA). Values of controls and samples were obtained through extrapolation from a reference curve.

Repeatability and within-laboratory precision studies of the ELISAcheck Collagen Binding Assay (Precision BioLogic; Halifax, NS, Canada) resulted in coefficients of variation of less than 11%. A linear range of 0.01-3.54 IU/mL was determined, along with a limit of detection of 0.016 IU/mL and a lower limit of quantitation of 0.04 IU/mL. Samples tested from apparently healthy individuals resulted in a normal range of 0.54-2.17 IU/mL. The known VWD type 1 and type 2 samples were also analyzed by the ELISA, with 99% of samples having VWF:collagen binding below the normal reference range and an estimated 96% sensitivity and 87% specificity using a VWF collagen-binding/antigen cutoff ratio of 0.50.

The authors concluded that the VWF:collagen binding ELISA provides an accurate measure of collagen-binding activity that aids in the diagnosis and differentiation of type 1 from type 2 VWD. Although proper identification and typing of VWD requires a panel of assays to allow the best patient care and therapeutic management, the ELISAcheck Collagen Binding Assay is a valuable addition to the current VWD diagnostic toolbox. The study was published in the April 2013 issue of the International Journal of Laboratory Hematology.

Related Links:
Westmead Hospital
Molecular Devices
Precision BioLogic