TIGIT and B-cell chronic lymphocytic leukemia: Co-culture of CLL cells with autologous CD4+ T-cells, which were either depleted of PD-1+, TIGIT+, or PD-1+ TIGIT+ double-positive T-cells, revealed a reduced CLL cell viability in all of the depleted co-cultures, suggesting that these T-cell subsets enhance CLL cell survival [8].