Fig. 2.

Representative gating strategies for plasma cells and B-cells. A) Displays normal B-cells in a SMM participant. CD19⁺ B-cells were identified in the lymphocyte population using a histogram, and further gated as CD20⁺. Within the CD19⁺CD20⁺ B-cell population, B-cell subsets were identified by plotting CD38 against CD27, and confirmed as polyclonal through an Ig-Kappa × Ig-Lambda plot. B) Displays a SMM participant with greater plasma cell burden. Following the exclusion of debris and doublets (not shown) leukocytes were identified in a SSC-A × FSC-A plot. Plasma cells were then identified as CD38^brightCD138⁺ using a generous box gate. Clonal plasma cells were then identified as CD45^−/dimCD19⁻ and confirmed through light chain restriction. C) Displays a SMM participant with few plasma cells, comprising both clonal plasma cells and polyclonal plasma cells – identified as CD45⁺CD19⁺ and with polyclonal light chains. D) Displays a MREM participant on lenalidomide maintenance with detectable plasma cells, comprising only polyclonal plasma cells. SSC-A, side scatter-area; FSC-A, forward scatter-area; SMM, smouldering multiple myeloma; MREM, myeloma remission.