Definition of human cytomegalovirus-specific target antigens recognized by cytotoxic T cells generated in vitro by using an autologous lymphocyte system.

We developed an in vitro system for the generation of human cytomegalovirus (CMV)-specific cytotoxic T cells (CTL) that avoids the necessity of constituting a panel of HLA-typed fibroblasts. Autologous donor leucocytes were coated with CMV antigens and were used as both stimulator and target cells. With the use of this system, CMV-specific effector cells were efficiently generated from seropositive but not seronegative donors. These CMV-specific effectors were HLA-restricted and had characteristics of T cells. Maximum lymphoproliferation preceded the appearance of maximum CTL activity by 3 to 4 days, and a close correlation was seen between both activities. Mouse anti-CMV monoclonal antibodies were used in blocking experiments in an attempt to define target antigens recognized by CMV-specific cytotoxic lymphocytes. Monoclonal antibodies directed against an early CMV membrane antigen, against neutralization epitopes, or against nuclear inclusion body protein all specifically inhibited CMV-sensitized effector cell activity but did not affect influenza virus-specific lysis. Monoclonal antibodies directed against a normal cell determinant or against poliovirus did not affect CMV-specific CTL activity. CMV-immune cytotoxic T cells could be consistently and specifically inhibited in their lytic activity by pretreating antigen-coated target cells with monoclonal antibodies directed against CMV-related proteins.