Flow cytometry to detect LAG3 on clonally restricted B cells in DLBCL. Clonally expanded and nonclonally expanded CD20⁺ B-cell populations were detectable by forward/side scatter, CD10 and/or CD5 λ and κ light chain restriction flow cytometric analysis on fresh frozen deaggregated DLBCL lymph nodes. Representative flow cytometric plots show gating strategies and LAG3 staining in Case 1 (A), Case 2 (B), and Case 3 (C). In each case, clonally expanded CD20⁺ B cells were distinguished from nonclonally restricted CD20⁺ B-cell populations by gating on CD5⁺/κ⁺(or λ⁺) or CD10⁺/κ⁺ cells. sIg, soluble immunoglobulin.