CD28 and neoplasm: Figure 4E shows that all armored CAR γδ T cell populations secrete IL18 that is detectable by ELISA, independent of activation state. Following anti-CD3+CD28 crosslinking or co-culture with MDA-MB-468 tumor cells, IL18 biological activity was significantly elevated in +GzB-IL18-derived supernatants, albeit not to the level seen with +const. IL18 or +GzB-IL18/GzB (Figure 4F).