Tetramer staining and clonal analysis of LB-ADIR-1F–specific CTLs in the patient. PBMCs from the patient taken at several time points after SCT and DLI were stained with LB-ADIR-1F tetramers (▪), and serum paraprotein levels were measured (▴) (A). LB-ADIR-1F tetramer-positive cells present at week 7 after DLI were single-well sorted and expanded. TCRBV sequence analysis was performed on 44 reactive clones revealing TCRBV7S1 in 43 clones and TCRBV6S4 in 1 clone (B). Reanalysis of the patient sample was performed using counterstaining with TCRBV7 confirming a low percentage of TCRBV7-negative cells in the LB-ADIR-1F–positive population (C). Reactivity of TCRBV7S1- (▪) and TCRBV6S4- (▵) expressing clones was determined using ⁵¹Cr release assays on peptide-pulsed T2 cells (D) and EBV-LCL cells (E), demonstrating that TCRBV6S4-expressing T cells displayed lower cytotoxicity.