CTLA4 and plasma cell myeloma: We chose to look at CTLA-4+ as a marker of exhaustion as uur group has previously studied Leflunomide in multiple myeloma 5TGM1 model in C57BL/KaLwRijHsd mice, which showed significantly differences in only CTLA-4 CD8+ T cells but not other markers of T cell exhaustion (LAG3, PD1, 2B4 and KLRG1) 18.