Clinical Significance of Immunophenotyping of Bone Marrow Cells in Multiple Myeloma

Aim. To analyze the relationship between expression of aberrant CD45, CD19, CD56 markers on the plasma cells and clinical and laboratory findings and prognostically significant parameters in patients with multiple myeloma (MM). Methods. This scientific research includes data on clinical investigation and immunophenotyping of bone marrow cells obtained from 64 MM patients treated in the N.N. Blokhin Russian Cancer Research Center over the period from 2004 to 2015. The three-color flow cytometry was performed using a direct immunofluorescence technique (CD38-PerCP, CD138-FITC monoclonal antibodies) and PE-conjugated monoclonal antibodies against CD45, CD19, and CD56. Results. Comparison of average values of the total count of plasma cells, the number of plasmablasts, proplasmacyte and mature plasma cells (according to the myelogram) and comparison of these data with the level of expression of the CD19 marker demonstrated a significant relationship between the CD19 negative immunophenotype and both a higher level of the total count of plasma cells and immature plasma cells. There also was a significant correlation between the CD19 negative immunophenotype and a higher level of C-reactive protein, which is significant prognostic factor in MM. In addition, there was a significant relationship between the CD19 negative phenotype and a higher percentage of young neutrophils in blood, i.e. with a more frequent “left shift”. The CD56 negative phenotype is associated with plasmablastic morphology of plasma cells and with the presence of plasma cells in the peripheral blood. Plasma cell leukemia is more common in patients with СD56 negative phenotype of myeloma cells. The CD45 negative immunophenotype was associated with a higher level of k-type FLCs, Bence-Jones proteinuria and with a higher serum creatinine, than in the cases of CD45 positive phenotype. Conclusion. The study of the immunophenotype of plasma cells in MM has important scientific and practical significance and requires further study.