Delayed allograft rejection by the suppression of class II transactivator

(CIITA) down-modulation on allograft rejection. To inhibit the function of CIITA, we constructed a series of CIITA mutants and found one exhibiting the dominant-negative effect on the regulation of major histocompatibility complex (MHC) class II expression. To test whether the CIITA dominantnegative mutant reduces immunogenecity, CIITAtransfected melanoma cells were injected into allogeneic host and assessed for immune evading activity against host immune cells. We demonstrated that the CIITA dominant-negative mutant allowed tumor nodules to develop earlier in the lung than control by this tumor challenge study. Furthermore, skin grafts deficient for CIITA also survived longer than wild-type in allogeneic hosts. Both the tumor challenge and skin graft studies suggest the inhibition of CIITA molecules in donor tissue would be beneficial to the control of allo-response. KCI Citation Count: 1