Evaluation of B cell maturation antigen (CD269) in comparison to CD138 for identifying multiple myeloma in Egyptian patients

Background B cell maturation antigen (BCMA) is primarily expressed on B-cell lineage cells, as well as on plasmablasts. It is selectively induced during plasma cell differentiation to support the survival of long-lived plasma cells (PCs) in the bone marrow. BCMA expression is significantly higher in malignant PCs compared with normal PCs and increases as the disease progresses. We focused in this study on BCMA expression on malignant PCs by flow cytometry in comparison with CD138 expression to determine if it can be included in standard panels and correlate its expression with diagnostic and prognostic multiple myeloma (MM) markers. Results The overall median percentage and mean fluorescence intensity (MFI) of CD138 in all patients was 4.75% and 23.25 where group I (newly diagnosed/relapsed MM patients) demonstrated a statistically significant higher median percentage (11.1%) with wide range of variability (0.02–76.4%) and lower MFI (16.2) compared with group II (minimal residual disease (MRD)) ( P 0.015 and 0.002). In contrast, the overall median percentage and MFI of BCMA in all patients was 43.6% and 2.54, being significantly higher in group II (91.7%) and (3.44) ( P <0.001 and 0.04). A cut off value of less than or equal to 5.2% for CD138 and greater than 37.8% for BCMA with the highest BCMA sensitivity and specificity than CD138% expression was found in detecting MRD samples. Conclusion BCMA can be used as a marker for MM diagnosis owing to its high expression on malignant PCs especially in MRD cases, and should be routinely used on flow cytometry panels to detect MM cells.