Background: To expand the criteria of immune thrombocytopenic purpura (ITP), which is a diagnosis of exclusion, we analyzed proteins separated by 1-dimensional gel electrophoresis of the retained fraction in a Con A-Sepharose column from ITP patients' sera.
Methods: Serum samples were from 19 adult patients with chronic ITP, 9 patients with thrombocytopenia of decreased production, and 20 healthy controls. Samples were applied to a Con A-Sepharose column, and the retained fraction was subjected to 10% SDS-PAGE. The % area of each densitometric protein peak was compared between the two groups and proteins in each band were identified using LC-MS/MS.
Results: Eleven protein bands were distinctly separated by 1-dimensional electrophoresis. The percent area of bands #2 and #3 were significantly higher in ITP patients than in controls. The percent area of band #2 (p<0.01) was significantly higher in ITP patients than in non-ITP patients. We identified alpha(2)-macroglobulin, ceruloplasmin (Cp), and C3 in band #2 and complement factor B in #3 band. Serum concentrations of alpha(2)-macroglobulin and Cp were significantly higher in ITP patients than in controls. Serum concentrations of Cp were significantly higher in ITP patients than in non-ITP patients (p=0.0005). Serum complement factor B concentrations were significantly higher in ITP patients and non-ITP patients than in controls. ROC analysis showed that the total percent area of bands #2 and #3, and Cp had higher diagnosis availability for ITP patients when compared with controls and non-ITP patients, respectively.
Conclusions: Measurement of Cp separated by the present method could be useful for the diagnosis of ITP in the presence of thrombocytopenia and a non- or low-inflammatory state.