Discovery and identification of potential biomarkers in a prospective study of chronic lymphoid malignancies using SELDI-TOF-MS

The accurate diagnosis of the different forms of chronic mature B-cell lymphocytic malignancies is of primary importance to determine an appropriate and efficient treatment. Usually, the diagnosis is achieved by morphology and immunophenotyping. Nevertheless, the diagnostic tools available are not able to discriminate pathologies with variable evolution, or to classify some of them. To discover new biomarkers, we used peptide and protein profiling SELDI-TOF-MS, to analyze 39 chronic B-cell malignancies and 20 control serum samples. Markers of interest were subsequently identified and characterized. In the obtained SELDI-MS profiles, most of the differences were observed in three mass ranges (m/z = 13 000; m/z = 9000; m/z < 2000). Identification of these biomarkers was achieved either by direct enrichment on the ProteinChip arrays followed by on-chip-MS/MS or by chromatographic fractionation, 1D-gel followed by nanoLC-MS/MS analysis. An increase of a sulfite form of transthyretin (13841Da) was observed in the patient group. A second set of markers at 8.6 and 8.9 kDa was identified as complement related fragment proteins, the C3a and C4a anaphylatoxins. In the low mass range, several peptides originating from N-terminal and C-terminal processing of the C3 alpha and C4 alpha chains were specifically observed in 38% of the patient sera, but in none of the control sera. This study emphasizes the usefulness of mass spectrometry studies in such malignancies.