IL21 and infection: Concurrently, Bcl-6 protein level was remarkably lower in Uba3-deficient CD4+ T cells than in Uba3-sufficient counterparts at day 7 of infection (Fig 8C), and the proportion of IL-21-producing CD4+ T cells in the spleen was also found to be lower in Uba3ΔT mice at this time (Fig 8D).