Author(s): Manicassamy S, Yin D, Zhang Z, Molinero LL, Alegre ML,
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Abstract Protein kinase C (PKC)-theta mediates the critical TCR signals required for T cell activation. Previously, we have shown that in response to TCR stimulation, PKC-theta-/- T cells undergo apoptosis due to greatly reduced levels of the anti-apoptotic molecule, Bcl-xL. In this study, we demonstrate that PKC-theta-regulated expression of Bcl-xL is essential for T cell-mediated cardiac allograft rejection. Rag1-/- mice reconstituted with wild-type T cells readily rejected fully mismatched cardiac allografts, whereas Rag1-/- mice reconstituted with PKC-theta-/- T cells failed to promote rejection. Transgenic expression of Bcl-xL in PKC-theta-/- T cells was sufficient to restore cardiac allograft rejection, suggesting that PKC-theta-regulated survival is required for T cell-mediated cardiac allograft rejection in this adoptive transfer model. In contrast to adoptive transfer experiments, intact PKC-theta-/- mice displayed delayed, but successful cardiac allograft rejection, suggesting the potential compensation for PKC-theta function. Finally, a subtherapeutic dose of anti-CD154 Ab or CTLA4-Ig, which was not sufficient to prevent cardiac allograft rejection in the wild-type mice, prevented heart rejection in the PKC-theta-/- mice. Thus, in combination with other treatments, inhibition of PKC-theta may facilitate achieving long-term survival of allografts.
This article was published in J Immunol
and referenced in Journal of Clinical & Cellular Immunology