Human cytomegalovirus infections have a major negative effect on morbidity and mortality of immunosuppressed allograft recipients and indirectly on graft function and survival. The adoptive antiviral T-cell therapy is a novel therapeutic tool to restore immune competence after solid organ transplantation. Till now, the antiviral T-cell products mainly focused on cytotoxic CD8(+) T cells, whereas CD4(+) T cells played a minor role. Here, we demonstrate the importance of CD4(+) T cells within T-cell lines specific for human cytomegalovirus besides its essential support for the quality of CD8(+) T-cell memory. Virus-specific CD4(+) T cells elicit profound functionality after rechallenge (multicytokine secretors, CD137, CD154, and CD107a expression and killing of infected target cells). The CD4(+) T cells show predominantly a Th1 phenotype with cytolytic properties that is mainly perforin-dependent. The data demonstrate the significance of CD4(+) T cells within T-cell products to achieve a successful adoption with enhanced efficacy.
