PLoS Pathog

Cytomegalovirus (CMV) is a leading infectious cause of morbidity in immune-compromised patients. γδ T cells have been involved in the response to CMV but their role in protection has not been firmly established and their dependency on other lymphocytes has not been addressed. Using C57BL/6 αβ and/or γδ T cell-deficient mice, we here show that γδ T cells are as competent as αβ T cells to protect mice from CMV-induced death. γδ T cell-mediated protection involved control of viral load and prevented organ damage. γδ T cell recovery by bone marrow transplant or adoptive transfer experiments rescued CD3ε-/- mice from CMV-induced death confirming the protective antiviral role of γδ T cells. As observed in humans, different γδ T cell subsets were induced upon CMV challenge, which differentiated into effector memory cells. This response was observed in the liver and lungs and implicated both CD27+ and CD27- γδ T cells. NK cells were the largely preponderant producers of IFNγ and cytotoxic granules throughout the infection, suggesting that the protective role of γδ T cells did not principally rely on either of these two functions. Finally, γδ T cells were strikingly sufficient to fully protect Rag-/-γc-/- mice from death, demonstrating that they can act in the absence of B and NK cells. Altogether our results uncover an autonomous protective antiviral function of γδ T cells, and open new perspectives for the characterization of a non classical mode of action which should foster the design of new γδ T cell based therapies, especially useful in αβ T cell compromised patients

γδ T cells get adaptive.

Throughout ontogeny, the γδ TCR repertoire in human blood becomes less diverse and more focused, yet is private in nature, and specific adult γδ T cell subsets undergo substantial clonal expansion after challenge with cytomegalovirus

γδT cells elicited by CMV reactivation after allo-SCT cross-recognize CMV and leukemia.

Human cytomegalovirus (CMV) infections and relapse of disease remain major problems after allogeneic stem cell transplantation (allo-SCT), in particular in combination with CMV-negative donors or cordblood transplantations. Recent data suggest a paradoxical association between CMV reactivation after allo-SCT and reduced leukemic relapse. Given the potential of Vδ2-negative γδT cells to recognize CMV-infected cells and tumor cells, the molecular biology of distinct γδT-cell subsets expanding during CMV reactivation after allo-SCT was investigated. Vδ2(neg) γδT-cell expansions after CMV reactivation were observed not only with conventional but also cordblood donors. Expanded γδT cells were capable of recognizing both CMV-infected cells and primary leukemic blasts. CMV and leukemia reactivity were restricted to the same clonal population, whereas other Vδ2(neg) T cells interact with dendritic cells (DCs). Cloned Vδ1 T-cell receptors (TCRs) mediated leukemia reactivity and DC interactions, but surprisingly not CMV reactivity. Interestingly, CD8αα expression appeared to be a signature of γδT cells after CMV exposure. However, functionally, CD8αα was primarily important in combination with selected leukemia-reactive Vδ1 TCRs, demonstrating for the first time a co-stimulatory role of CD8αα for distinct γδTCRs. Based on these observations, we advocate the exploration of adoptive transfer of unmodified Vδ2(neg) γδT cells after allo-SCT to tackle CMV reactivation and residual leukemic blasts, as well as application of leukemia-reactive Vδ1 TCR-engineered T cells as alternative therapeutic tools.Journal ArticleResearch Support, Non-U.S. Gov'tSCOPUS: ar.jinfo:eu-repo/semantics/publishe