Fluorescence In Situ Hybridization on Enriched CD138-Positive Cells in Plasma Cell Myeloma
To validate plasma cell enrichment technique for improving the detection of cytogenetic abnormalities in the Plasma cell myeloma (PCM)/multiple myeloma (MM). We compared the abnormality detection rate for overnight unstimulated bone marrow cultures to that for the plasma cell enriched fractions obtained with the use of CD138-coated immunomagnetic beads. Average enrichment factor (EF) was 11. One or more abnormalities were detected in 90% of enriched samples vs. 65% of non-enriched samples, thus resulting in a significantly higher detection rate of total cytogenetic abnormalities in enriched plasma cells (p=0.0038). Additional findings of RB1 deletion, TP53-, 1p-, 1q+ and IGH@ rearrangement seen in the 25% of enriched samples could contribute to the altered risk in the patient. One of the three cases with plasma cells as low as 1% by morphology was positive for a residual disease marker in the enriched sample and negative in the non-enriched sample. The plasma cell enrichment technique increased the detection rate of diagnostic and prognostic markers and is a very sensitive method for detecting minimal residual disease.