GÉTICA 2021

14 VII FORO DE I nmunología Traslacional e INMUNOTERAPIA DEL CÁNCER SS cells or the CDR3ß of their clonal TCR using cell (Fig. 2A) and CDR3ß (Fig. 2B) immuniza- tion, respectively and T-cell hits that respond to a peptide pool (of 8 tested pools) contain- ing long peptides derived from the SS TCR CDR3ß sequence and from an RNAseq-over- expressed protein (MAGE-1) (Fig. 3). Conclusions: TCR CDR3ß from SS cells can be a target for the development of specific an- tibodies as potential immunotherapy tools. Normal peptides expressed or overexpressed by SS cells can induce T immune responses as potential immunotherapy tools. Support: AECC PROYE20084REGU. ing was done on SS vs. non-SS CD4 cells as de- fined by flow cytometry using CD26 and PD-1. For in vitro expansion of SS peptide-specific T cells, SS patient-derived non-SS PBMCs were first stimulated in vitro with IL-2 and pooled HLA class I+II SS peptides defined by SS WGS, WES and RNAseq-based predictions or peptidome studies and second, exposed to autologous DC pre-loaded with peptide pools studying cy- tokine production by flow cytometry. Results: We have obtained preliminary data on aims 1 and 2 studying three SS patients (Fig. 1) with monoclonal T-cell lymphomas, including potential mouse antibodies against Figure 1. CD26 vs. PD-1 distribution within CD3+ CD4+ lymphocytes from a healthy donor and the three patients studied (SS1-3). The % of Sézary cells are defined as CD26neg PD-1+ and indicated in red.