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Medline ® Abstract for Reference 80

of 'Principles of cancer immunotherapy'

Triggering of OX40 (CD134) on CD4(+)CD25+ T cells blocks their inhibitory activity: a novel regulatory role for OX40 and its comparison with GITR.
Valzasina B, Guiducci C, Dislich H, Killeen N, Weinberg AD, Colombo MP
Blood. 2005 Apr;105(7):2845-51. Epub 2004 Dec 9.
OX40 (CD134) is a member of the tumor necrosis factor (TNF) receptor family that is transiently expressed on T cells after T-cell receptor (TCR) ligation. Both naive and activated CD4(+)CD25+ regulatory T cells (T reg's) express OX40 but its functional role has not been determined. Since glucocorticoid-induced tumor necrosis factor receptor (GITR), a related TNF receptor family member, influences T reg function, we tested whether OX40 might have similar effect. Triggering either GITR or OX40 on T reg's using agonist antibodies inhibited their capacity to suppress and restored effector T-cell proliferation, interleukin-2 (IL-2) gene transcription and cytokine production. OX40 abrogation of T reg suppression was confirmed in vivo in a model of graft-versus-host disease (GVHD). In a fully allogeneic C57BL/6>BALB/c bone marrow transplantation, GVHD was lethal unless T reg's were cotransferred with the bone marrow and effector T cells. Strikingly, T reg suppression of GVHD was abrogated either by intraperitoneal injection of anti-OX40 or anti-GITR monoclonal antibodies (mAbs) immediately after transfer, or by in vitro pretreatment of T reg's with the same mAbs before transfer. Cumulatively, the results suggest that in addition to controlling memory T-cell numbers, OX40 directly controls T reg-mediated suppression.
Immunotherapy and Gene Therapy Unit, Department of Experimental Oncology, Istituto Nazionale per lo Studio e la Cura dei Tumori, Via Venezian 1, 20133 Milan, Italy.