Fig. 1

Jchain target identification and subsequent selection of promising T-cell clones recognizing Jchain peptides in HLA-A1, A24, A3 and A11. A JCHAIN microarray data (probe ILMN_2105441) from an Illumina HT12.0 microarray dataset (GSE76340) displaying gene expression levels in mean fluorescence intensities (MFI) in healthy tissue of non-hematopoietic origin (in gray), healthy tissue of hematopoietic origin (in blue), healthy subsets containing B cells (yellow) and B- and plasma cell malignancies (in red). Per healthy tissue gene expression was measured in 2–7 samples (mean; 3.4). Abbreviations: ALL, acute lymphoblastic leukemia; CLL, chronic lymphocytic leukemia; MM, multiple myeloma; EBV-LCL, Epstein–Barr virus-transformed lymphoblastoid cell lines; PBMC, peripheral blood mononuclear cells; BMMC, bone marrow mononuclear cells; HPC, hematopoietic precursor cells; DC, dendritic cells; MΦ1, type 1 macrophages; MΦ2, type 2 macrophages; IFN-γ, interferon-γ; HUVEC, human umbilical vein endothelial cells; PTEC, proximal tubular epithelial cells. B Violin plot of JCHAIN expression (top graph) in 133 MM samples and 5 healthy plasma cell (PC) samples. Samples were enriched for CD138; therefore, CD138 (SCD1) expression is displayed as positive control (bottom graph). Data were extracted from publicly available dataset GSE13591. Dashed lines indicate background level for negative expression values. Dotted line indicates an arbitrary cutoff for samples expressing JCHAIN (expression value > 1000). C Example of verification of peptide identification by mass spectrometry. Tandem mass spectra of ISDPTSPLRTR peptide eluted from HLA-A3 positive U266 MM cells as well as HLA-A11 positive UM9 MM cells (top graph). Corresponding tandem mass spectra of synthetic ISDPTSPLRTR peptide (bottom graph). D, E IFN-γ production by Jchain-specific T cells clones after overnight co-culture measured by ELISA. Graphs are separated based on peptide-HLA specificities. Averages of technical duplicates are depicted. D Jchain T-cell clones co-cultured with K562 target cells transduced with target HLA alleles (-A1, -A24, -A3, or –A11) without or with additional transduction of the JCHAIN gene (+ Jchain). E T-cell clones overnight stimulated with antigen negative K562 cells transduced with target HLA molecules HLA-A1, -A24, -A3 or -A11 loaded with decreasing concentrations of Jchain peptides