[Limitations in quantitation of the biomarker CCL18 in Gaucher disease blood samples by SELDI]
>>Biochim Biophys Acta. 2006 Aug 22; [Epub ahead of print]
Limitations in quantitation of the biomarker CCL18 in Gaucher disease blood samples by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry.
van Breemen MJ, Bleijlevens B, de Koster CG, Aerts JM.
Clinical Proteomics Facility, Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Meibergdreef 15, 1105AZ Amsterdam, The Netherlands.
SELDI-TOF MS assisted the discovery of the chemokine CCL18/PARC as plasma biomarker for pathological storage cells in Gaucher disease patients. Prognostic elevation of CCL18 in blood of Gaucher patients has been confirmed by ELISA. Given its low molecular mass, positive charge, and relatively high abundance, CCL18 seems a particular attractive protein for SELDI-TOF based quantitation. Therefore, we determined CCL18 levels in plasma using SELDI-TOF MS and ELISA, in parallel. CCL18 levels in some blood samples were significantly underestimated when determined by SELDI-TOF MS. Spiking of recombinant CCL18 indicated that its detection by SELDI-TOF MS is strongly determined by the nature of the sample, even markedly varying between samples obtained from one donor at different time points. Independent of the total CCL18 concentration in blood only 1-10% of the chemokine bound to the ProteinChip(R) Array. Even when comparable amounts of CCL18 from distinct samples were bound to the ProteinChip(R) Array, diverse peak intensities could be observed. Thus, limited binding capacity and sample-dependent suppression of CCL18 ionization contribute significantly to the final peak intensity. In conclusion, SELDI-TOF MS offers no reliable procedure to quantitatively monitor CCL18 levels in blood and thus cannot be applied in evaluation of disease status of Gaucher patients.<<
Not like monitoring of Gaucher's disease is a big market, but this is not the kind of study one likes to see. Makes me wonder if they got sloppy with the samples. We may not ever know, and the negative result won't help. Emphasizes the importance of sample handling and prep, as I've harped on for some time now. But also provides ammo to the naysayers, and I'm beginning to wonder if they're right. Sigh. Quest, say something; get me out of this thing.
Cheers, Tuck |
