Mice deficient in PKC theta demonstrate impaired in vivo T cell activation and protection from T cell-mediated inflammatory diseases

In the present study we have characterized T cell-driven immune function in mice that are genetically deficient in PKC theta. In response to simple immunologic stimulation invoked by in vivo T cell receptor (TCR) cross-linking, these mice showed significantly depressed plasma cytokine levels for IL-2, IL-4, IFN gamma, and TNF alpha compared to wild-type (WT) mice. In parallel, spleen mRNA levels for these cytokines were reduced, and NF-kappa B activation was also reduced in PKC theta knockouts (KO). Injection of allogeneic cells into the footpad of PKC theta deficient mice provoked a significantly diminished local T cell response compared to WT mice similarly challenged. Unlike comparable cells from wild type mice, CD45RBhi T cells harvested from PKC theta deficient mice failed to induce colitis in the SCID-CD45RB cell transfer model of IBD. In another T cell-dependent model of inflammatory disease, PKC theta deficient animals developed far less severe neurologic signs and reduced spinal cord inflammatory cell infiltrate compared to WT controls in the MOG-induced EAE model. A fundamental role for PKC theta in T cell activation and in the development of T cell-mediated inflammatory diseases is indicated by these results.