Purification of cytomegalovirus-specific CD8 T cells from peripheral bloodusing HLA-peptide tetramers

Cytomegalovirus (CMV) reactivation and disease remains an important clinica l problem for patients after allogeneic stem cell transplantation. Impaired cellular immune control of viral replication is responsible for viral reac tivation, and transfer of CMV-specific T cells from transplant donors can b e effective in providing protection. Recent reports have indicated that the frequency of CMV-specific CD8(+) T cells in the peripheral blood of health y donors is surprisingly high. Here we demonstrate that by using a combinat ion of human leucocyte antigen (HLA) Class I-peptide tetramers and magnetic selection it is possible to select CMV-specific T cells from CMV antibody- positive individuals to high purity. Reliable purification of CMV-specific T cells up to 99.8% of CD8(+) cells was possible within hours. even when st arting with a precursor frequency of <0.1% of peripheral blood CD8(+) T cel ls. CMV-specific T cells remained functional after the selection process. T his novel form of antigen-specific T-cell selection should facilitate the s election of T cells for cellular immunotherapy to treat or prevent CMV dise ase after transplantation. In addition, this technique could potentially be applied to many antigens including against other infective agents and tumo ur-specific antigens.