Detection of Myeloma Cells in Peripheral Blood with Triple-ColorFlow Cytometry: Evaluation of Minimal Residual Disease

Overview

Background.
The aim of this study was to evaluate significance of CD 38++45-54+, CD 38++45-56+ and CD38++45-138+ cells counts in peripheral blood of patients with multiple myeloma for monitoring of the minimalresidual disease.Methods and Results. A triple-color flow cytometric analysis was used for this purpose. Peripheral blood of29 patients with multiple myeloma who underwent high dose chemotherapy and autologous stem cells transplantationwas repeatedly analysed. Counts of myeloma cells in peripheral blood were compared to serum monoclonalimmunoglobulin concentration, serum calcium level, serum C - reactive protein, serum b2microglobulin, and numberof myeloma cells in bone marrow (morphology). From 29 patients in this study, 5 patients have relapsed. Patientsin relapse had significantly higher counts of CD 38++45-54+, CD 38++45-56+ and CD 38++45-138+ cells inperipheral blood than patients in remission (geometrical average: 12,41; 6,20; 14,45 cells/ ml versus 4,08; 2,87; 2,58cells/ml). The number of these cells correlated well with serum monoclonal immunoglobulin level and counts ofmyeloma cells in bone marrow.Conclusion. The authors conclude that the longitudinal multi-color flow cytometric analysis of CD 38++45-54+,CD 38++45-56+ and CD 38++45-138+ cells in peripheral blood of patients with multiple myeloma is a useful methodfor evaluation of the disease activity. Significance of peripheral myeloma cells count for prediction of the relapseof the multiple myeloma remains to be evaluated.

Key words:
minimal residual disease, multiple myeloma, flow cytometry.