Dissecting the role of CBLB in human T cell activation and suppression

Cbl-b is a negative regulator of T cell activation and in murine models a lack of CBLB results in resistance of T effectors to Tregs, a feature of T cells in many autoimmune diseases. Here, we used trackable gene-editing approaches to knock out CBLB in primary human CD4+ T cells. We found that CBLB-KO CD4+ T cells were hyper-proliferative and produced excess amounts of IL-2 at baseline and upon TCR stimulation. CBLB-KO CD4+ T cells were resistant to Treg suppression in vitro, which was partially reversed by blockade of IL-2. RNAseq and puromycin incorporation assays demonstrate that CBLB-KO CD4+ T cells can overcome Treg suppression on the transcriptional and translational level resulting in the overproduction of cytokines to drive the proliferation and activation of Teffs. These findings also highlight a potential mechanism of Teff resistance in human autoimmune disease and the power of gene editing of primary T cells to explore disease mechanisms. 24 samples total. 4 donors, 2 treatments (CBLB-KO or AAVS1-KO), 3 stimulations (none, CD3CD28 beads, CD3CD28 beads + Treg exposure)