Background. With the advent of multiparameter flow cytometry (FC) it became possible simultaneously analyze normal and malignant plasma cells (PC) in multiple myeloma (MM) patients. There is some data that residual normal bone marrow plasma cells (nBMPC) is of prognostic signifi cance in plasma cells dyscrasias. There is no data about clinical value of immunophenotypically normal peripheral blood circulating plasma cells (nCPC).
Material and methods. In this study we evaluated clinical significance of normal plasma cells detection by FC in peripheral blood (PB) and bone marrow (BM) compartments of refractory or relapsed (RR) multiple myeloma (MM) patients. For sample analysis we used 2 tubes stained with antibody combinations CD56/CD138/CD45/CD19/CD38/CD20 and cLambda/cKappą/CD138/CD19/CD38/CD56.
Results. PB and BM samples taken at the same time from 40 relapsed/refractory MM patients and 11 healthy controls (HC) were analyzed. We were able to detect nCPC and nBMPC subpopulation in 57.5% and 90% of MM patients, respectively. We did not find any clinical significance of nCPC detection at baseline, however increase of nCPC in response to treatment was associated with prol onged time to progression (TTP). We also showed that proportion of residual nBMPC to all BMPC is of prognostic significance in advanced MM patients.
Conclusions. Our finding supports clinical value of nPC identification for advanced MM patients, and use of FC rather than light microscopy for BMPC compartment analysis before treatment.
