HUMAN ADENOVIRUS-SPECIFIC CD8(-CELL RESPONSES ARE NOT INHIBITED BY E3-19K IN THE PRESENCE OF GAMMA-INTERFERON() T)

Adenovirus has considerable potential as a gene therapy vector, but re cent animal data suggest that transduced cells are destroyed by adenov irus-specific cytotoxic T-lymphocyte (CTL) responses. Therefore, it wi ll be important to develop strategies to evade adenovirus-specific CTL responses in humans. As a first step, an assay was developed to detec t and characterize human CTLs directed against adenovirus. Adenovirus- specific CTL responses were demonstrated to be present in four of five healthy adults by in vitro stimulation of peripheral blood mononuclea r cells with autologous fibroblasts infected with the adenovirus type 2 (Ad2) E3 deletion mutant Ad2(+)ND1. Killing by adenovirus-specific C TLs was major histocompatibility complex class I restricted and was do cumented to be mediated by CD8(+) T cells. Wild-type-Ad2-infected cell s were poor CTL targets compared with cells infected with the E3 delet ion mutant because of the expression of E3-19K, an early viral glycopr otein which prevents transport of major histocompatibility complex cla ss I antigens out of the endoplasmic reticulum to the cell surface. Ho wever, preincubation of targets,vith gamma interferon resulted in enha nced killing of wild-type-Ad2-infected cells, to levels comparable to those obtained with Ad2(+)ND1-infected cells. Radioimmunoprecipitation analysis revealed that gamma interferon not only increased the synthe sis of class I antigens but also allowed excess molecules to escape fr om the endoplasmic reticulum. It is concluded that E3-19K expression i n adenovirus-infected cells inhibits human CTL recognition in vitro bu t that gamma interferon may help overcome the E3-19K effect during acu te infection in vivo.