CYTOTOXIC T-LYMPHOCYTE TARGET PROTEINS AND THEIR MAJOR HISTOCOMPATIBILITY COMPLEX CLASS-I RESTRICTION IN RESPONSE TO ADENOVIRUS VECTORS DELIVERED TO MOUSE-LIVER

The activation of cytotoxic T lymphocytes (CTLs) to cells infected wit h adenovirus vectors contributes to problems of inflammation and trans ient gene expression that attend their use in gene therapy. The goal o f this study was to identify in a murine model of liver gene therapy t he proteins that provide targets to CTLs and to characterize the major histocompatibility complex (MHC) class I restricting elements. Mice o f different MHC haplotypes were infected with an E1-deleted adenovirus expressing human alkaline phosphatase (ALP) or beta-galactosidase as a reporter protein, and splenocytes were harvested for in vitro CTL as says to aid in the characterization of CTL epitopes. A library of vacc inia viruses was created to express individual viral open reading fram es, as well as the ALP and lacZ transgenes. The MHC haplotype had a dr amatic impact on the distribution of CTL targets: in C57BL/6 mice, the hexon protein presented by both H-2K(b) and H2D(b) was dominant, and in C3H mice, H2D(k)-restricted presentation of ALP was dominant. Adopt ive transfer of CTLs specific for various adenovirus proteins or trans gene products into either Rag-I or C3H-scid mice infected previously w ith an E1-deleted adenovirus verified the in vivo relevance of the ade novirus-specific CTL targets identified in vitro. The results of these experiments illustrate the impact of Ir gene control on the response to gene therapy with adenovirus vectors and suggest that the efficacy of therapy with adenovirus vectors may exhibit considerable heterogene ity when applied in human populations.