Cytomegalovirus-specific cellular immune responses and viremia in recipients of allogeneic stem cell transplants

The immune suppression inherent in allogeneic stem cell transplantation (SC T) offers a favorable environment for infection by opportunistic agents, su ch as human cytomegalovirus (CMV). Despite the application of potent antivi ral prophylaxis, patients remain at risk for CMV infection until adequate i mmunity is restored. CMV-specific CD8(+) T cell counts were monitored, usin g HLA-A2 tetrameric complexes, to establish the level of immune response to the viral phosphoprotein UL83 in patients after allogeneic SCT. Correlatin g this with viral replication and clinical status shows that the level of t etramer-positive T cells provides an assessment of CMV immune reconstitutio n after stem cell transplantation. Most patients with seropositive donors d id reconstitute long-term CMV immunity, unless prolonged immunosuppression to control graft-versus-host disease was induced. Together with polymerase chain reaction testing, this technique provides measurable parameters that can be a guide to therapeutic decision making and can form the basis of CMV immunotherapy.