IL18 and acute lymphoblastic leukemia: To determine whether MS5-secreted IL-18 could affect T-ALL cell proliferation, the expression of the α and β chains of the IL-18 heterodimer receptor (IL-18Rα and IL-18Rβ) was quantified in T-ALL samples and compared with that of normal umbilical cord blood (UCB) CD7+ T cells (Fig 3A and not shown).