INTERFERON-?? RECEPTOR SIGNALING IS NOT REQUIRED IN THE EFFECTOR PHASE OF THE ALLOIMMUNE RESPONSE1

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Abstract
Background. Gene transcripts for the Th1 cytokines interleukin (IL)-2 and interferon-γ (IFN-γ) are frequently detected during allograft rejection. The relative importance of these cytokines in facilitating allograft rejection is unclear. Recently, we have shown that IL-2-deficient mice reject islet allografts. In the IL-2-deficient system, IFN-γ gene transcripts are abundantly expressed. Methods. To determine the relative importance of IFN-γ-dependent effector mechanisms in mediating allograft rejection, the present study utilized IFN-γ receptor-deficient mice as islet allograft recipients. Grafts were analyzed by immunohistology, and cytokine expression was measured by competitive template reverse transcriptase polymerase chain reaction. Results. IFN-γ receptor-deficient mice reject islet allografts by a process that is T cell-dependent. Although IFN-γ receptor signaling is absent, these mice do not show a clear Th2 type response. Conclusion. Although the signals evoked through the IFN-γ receptor may play a role, they are not essential to allograft rejection.