INTERFERON-GAMMA RECEPTOR SIGNALING IS NOT REQUIRED IN THE EFFECTOR PHASE OF THE ALLOIMMUNE RESPONSE

Background. Gene transcripts for the Th1 cytokines interleukin (IL)-2 and interferon-gamma (IFN-gamma) are frequently detected during allogr aft rejection. The relative importance of these cytokines in facilitat ing allograft rejection is unclear. Recently, we have shown that IL-2- deficient mice reject islet allografts. In the IL-2-deficient system, IFN-gamma gene transcripts are abundantly expressed. Methods. To deter mine the relative importance of IFN-gamma-dependent effector mechanism s in mediating allograft rejection, the present study utilized IFN-gam ma receptor-deficient mice as islet allograft recipients. Grafts were analyzed by immunohistology, and cytokine expression was measured by c ompetitive template reverse transcriptase polymerase chain reaction. R esults. IFN-gamma receptor-deficient mice reject islet allografts by a process that is T cell-dependent. Although lFN-gamma receptor signali ng is absent, these mice do not show a clear Th2 type response. Conclu sion. Although the signals evoked through the lFN-gamma receptor may p lay a role, they are not essential to allograft rejection.