CD229 Expression on Bone Marrow Plasma Cells from Patients with Multiple Myeloma and Monoclonal Gammopathies of Uncertain Significance

Evaluation of CD229 as a new alternative plasma cell gating marker in the flow cytometric immunophenotyping of monoclonal gammopathies

“…The expression of CD229 on PC was strong in 90% of samples as compared with non-PC, allowing adequate separation of PC from the remaining hematopoietic cells. Carulli et al found that the MFI of CD229 on the logarithmic scale was relatively lower than that of CD138 and CD38 and expressed concern regarding the usefulness of CD229 (27). They found CD229 expression on 100% of PC and similarly, in this study CD229 was expressed on 100% of PCs in 97% (281/290) of samples.…”

“…We also demonstrated that the expression-pattern of CD229 on PC was homogenous in the majority of samples with a median CV of immunofluorescence of only 66.3 compared with 97.3 for CD138. CD38 is reportedly expressed on 100% PC (26,27) and we found that CD38 was positive on 100% PC in all samples except two. In this study, we assessed CD229 expression on non-PC in 20 additional BM samples and found similarly, that CD229 is also expressed, to a lesser extent, on dendritic cells, basophils, T-cells and mature B cells (Supporting Information Figure S1).…”

“…SLAM-family proteins like CD229 are being investigated as an alternative PC gating marker (26,27). In this study, we have explored the value of CD229 as a new reliable gating marker of PC for FCI in routine laboratory practice.…”

“…Of these, CD229 (LY9) has been found to be strongly expressed on PC. More recently, CD229 has been claimed to be a useful PC gating marker in FCI of MM (25)(26)(27). It is a surface molecule expressed on the cell membrane of B-cells, T-cells, monocytes, dendritic cells and PC.…”

“…Because of its expression on B-cells and PC, it has been suggested to be a potential target for monoclonal antibody (Moab) therapy in B-cell neoplasms (24). More recently, CD229 has been claimed to be a useful PC gating marker in FCI of MM (25)(26)(27). However, these studies are sparse and limited to a small cohort of patient samples enrolled in clinical trials.…”