CD8A and neoplasm: Originally, Dhodapkar et al. [17] demonstrated that both CD4+ and CD8+ BM T cells from MGUS patients can display vigorous cytotoxic responses against autologous PCs in vitro, but these activities were not evident when BM T cells from active MM patients were tested, thus supporting the notion that increasing tumor burden may correlate with cytotoxic T-cell exhaustion.