Functional specific-T-cell expansion after first cytomegalovirus reactivation predicts viremia control in allogeneic hematopoietic stem cell transplant recipients.

The use of preemptive antiviral therapy to prevent cytomegalovirus (CMV) disease in allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients might result in over-treatment, inducing drug-related toxicity and viral resistance. A search for predictive markers is needed to determine requirement for antiviral therapy. Clinical follow-up, in combination with the use of streptamers (STs) and cytokine-intracellular staining, could help to identify patients at high risk for CMV reactivations.

Streptamer technology allows accurate and specific detection of CMV-specific HLA-A*02 CD8 T cells by flow cytometry.

Background: Multimer technology is widely used to screen antigen-specific immune recovery after allogeneic hematopoietic stem cell transplantation (allo-HSCT) as it enables identification, enumeration, phenotypic characterization and isolation of virus-specific T-cells. Novel approaches of multimerization might improve on classical tetramer staining; however, their use as standard monitoring technique to quantify antigen-specific cells has not been validated yet. We have compared two of these available multimeric complexes: pentamer and streptamer to select the best strategy for the incorporation into clinical monitoring practice.

The immune response to cytomegalovirus in allogeneic hematopoietic stem cell transplant recipients.

Approximately, up to 70 % of the human population is infected with cytomegalovirus (CMV) that persists for life in a latent state. In healthy people, CMV reactivation induces the expansion of CMV-specific T cells up to 10 % of the entire T cell repertoire. On the contrary, CMV infection is a major opportunistic viral pathogen that remains a leading cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation.