Distribution and function of oligoclonal expanded PB T_TEcells. (A) Scatter plots of oligoclonal expansion of TCR-Vβ family–expressing populations within PB-T_TE cells of controls (n = 26), MGUS patients (n = 13), SMM patients (n = 10), and NDMM patients (n = 36). Expanded TCR-Vβ family–expressing populations were defined when the percentage of T_TE cells expressing that TCR-Vβ family was >3 SD higher than the mean frequency within CD8⁺T_N compartment of healthy blood donors (see “Materials and methods”). Each dot represents the percentage of PB-T_TE cells with an individual TCR-Vβ family expansion, with multiple expansions shown for each subject (average 3 expanded TCR-Vβ families per subject). The arrows indicate selected dominant TCR-Vβ family expansions that were tested for capacity to kill autologous CD38^hiPCs (n = 9; #12 to #20; see below, panel D). (B) Oligoclonal expansion of TCR-Vβ family–expressing populations in paired BM-T_TE and PB-T_TE of NDMM patients (n = 11, #1 to #11). Each colored segment in a stacked vertical bar indicates the proportion of an individual oligoclonal expansion within total BM-T_TE and PB-T_TE compartment. (C) Dot plots gated for CD3⁻CD14⁻ cells show CD38^hiPCs after a 2-hour culture assay with the target (CD3⁺T-cell-depleted BM MNCs) alone, the target with flow-sorted autologous oligoclonal expanded PB-T_TE cells expressing the subject’s dominant TCR-Vβ family, or the target with flow-sorted autologous PB-T_TE cells not expressing the dominant TCR-Vβ family (remaining PB-T_TE cells). Boxes and numbers indicate the percentage of CD38^hiPCs recovered in each culture condition. FSC, forward scatter. (D) Graph shows percentage of CD38^hiPCs recovered in culture with PB-T_TE cells expressing dominant TCR-Vβ family or with remaining PB-T_TE cells, normalized to the percentage of CD38^hiPCs recovered in culture with target only. The dominant TCR-Vβ family expansion from each of 9 tested patients (NDMM, #12-13,#15-20; SMM, #14) is indicated by an arrow in Figure 3A. (E) Dot plots show cell surface CD107a and intracellular IFN-γ expression. (F) Graph shows proportions of CD107a⁺T_TE cells (n = 4) in PB-T_TE cells expressing dominant TCR-Vβ family and remaining PB-T_TE cells after a 2-hour culture assay with target. (G) tSNE plots show distribution of Vβ13.1 and Vβ8 family–expressing PB-T_TE cells (top, indicated by red dotted circles) with high perforin and granzyme B expression (bottom) within PB-T_TE cells of NDMM #2. (H) Relationship between paired proportion of PB-T_TE cells expressing dominant TCR-Vβ family (presented as percentage of PB-T_TE cells) and CD69⁺T_TE cells (presented as percentage of BM-T_TE cells) in NDMM patients (n = 14) analyzed by linear regression model. *P < .05; **P < .01.