Preemptive control of graft-versus-host disease in a murine allogeneic transplant model using retrovirally transduced murine suicidal lymphocytes

Suicidal lymphocytes could greatly expand the role of allogeneic transplant ation by reducing graft-versus-host disease (GVHD) as a barrier to transpla ntation, but optimization of their use is hindered by the lack of adequate animal models. To develop an animal model that used retrovirally transduced suicidal lymphocytes in a GVBD setting, a well-characterized MHC-matched m urine transplant model (B10.BR --> AKR/J) was adapted. B10.BR splenic lymph ocytes stimulated with concanavalin B and interleukin 2 were infected with a retrovirus containing the low-affinity nerve growth factor receptor (LNGF R) and the HSV-TK gene and immunomagnetically selected; these LNGFR+/TK+ al logeneic lymphocytes were then cotransplanted with 1 X 10(7) bone marrow ce lls into lethally irradiated AKR/J recipients. The LNGFR+/TK+ donor lymphoc ytes persisted in the peripheral circulation for 6 months in both syngeneic and allogeneic settings, Doses of 2 x 10(6) TK+ allogeneic lymphocytes pro duced GVHD with a severity and time course similar to that induced by naive lymphocytes, Survival of TK+ allogeneic lymphocyte-bearing mice was signif icantly improved (P = 0.01) when ganciclovir (GCV; 2 mg/day) was administer ed on days 7-13 post transplant by i.p. injection, demonstrating that GVHD could be prevented. Fluorescence-activated cell sorting analysis demonstrat ed 4-fold reduction but persistent circulation of LNGFR+ lymphocytes in mic e treated with GCV at various time points 1-3 months after transplantation, demonstrating selective killing of GVHD-reactive cells. We conclude that r etrovirally transduced LNGFR+/TK+ murine lymphocytes can be produced, persi st after transplant, remain alloreactive, and can be killed by GCV administ ration, resulting in reduced GVHD.