Recognition of CMV pp65 protein antigen by human CD4 T-cell lines induced with an immunodominant peptide pool

Cellular immunity against cytomegalovirus (CMV) is essential for recovery from infection and control of viral latency. In immunocompromised hosts, this balance between CMV and cellular immunity is lost. Accordingly, restoration of the CD8 compartment specific for CMV is beneficial for immunocompromised patients. It is clear that CMV-specific CD4 cells provide helper functions facilitating long-term persistence of CD8 cells. Considering the dearth of data on CMV-specific T-helper cells, we investigated the CD4 responses to the immunodominant protein pp65 to define antigenic peptides. Such peptides were pooled and used to generate long-term T-cell lines. The lines were responsive to CMV and pp65. T cells were selected with individual peptides to produce monospecific lines for accurate definition of fine epitope specificity and to confirm human leukocyte antigen HLA-DR restriction. Furthermore, these lines lost alloreactivity, suggesting that they can be generated from the allodonor for adoptive immunoreconstitution of stem cell graft recipients.