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. 2026 Jul 13;16:1809955. doi: 10.3389/fonc.2026.1809955

Figure 3.

Panel A displays six flow cytometry dot plots identifying lymphocyte populations, with subsets colored green, blue, and black; axes include markers such as CD19, CD38, CD45, kappa, and lambda. Panel B contains three dot plots, highlighting a red cell population labeled P2, with axes and marker panels similar to those in panel A, demonstrating sequential gating and population isolation.

Flow cytometric immunophenotyping – identification of monoclonal plasma cells and discovery of the clonal B-cell population. (A) Monoclonal plasma cells (black, gate P1) express CD38 with cytoplasmic λ light chain restriction, while lacking CD19 and cytoplasmic κ light chain. (B) Reverse gating from cytoplasmic λ-positive cells within the lymphocyte gate (CD38-negative) identified a distinct population (red, gate P2) that lacked CD19 and CD38 but expressed λ light chain. This finding prompted additional B-cell lymphoma panel testing (see Figure 4).