RESUMO
Human adenovirus (HAdV) is a cause of significant morbidity and mortality in immunocompromised patients, especially after stem cell transplantation (SCT). Viral clearance has been attributed to CD4(+) T-cell responses against the Hexon-protein, but the frequency of specific T(HELPER) cells is extremely low or not detectable ex vivo and preference for different CD4(+) T-cell epitopes is variable among individuals. We therefore analyzed 44 healthy donors and 6 SCT-recipients for Hexon-specific CD4(+)-responses ex vivo, to identify epitopes which would be broadly applicable. We selected 19 candidate epitopes with predicted restriction to HLA-DR1/DR3/DR4/DR7; 16 were located within the highly conserved regions, indicating cross-reactivity of T cells among HAdV-subspecies. Ten epitopes induced CD4(+)-proliferation in >50% of individuals, confirmed by intracellular IFN-gamma detection. Three SCT recipients who recovered from an infection with HAdV displayed reactivity towards only a single hexon epitope, whereas healthy individuals were responsive to two to eight epitopes (median 3). The ex vivo detection of Hexon-specific CD4(+) T-cells, without any long-term culture in vitro, enables the detection and generation of HAdV-specific CD4(+) T cells for adoptive T-cell transfer against HAdV-infection post SCT.
Assuntos
Adenovírus Humanos/imunologia , Linfócitos T CD4-Positivos/imunologia , Proteínas do Capsídeo/imunologia , Epitopos de Linfócito T/imunologia , Antígenos HLA-DR/imunologia , Transplante de Células-Tronco , Adolescente , Células Cultivadas , Criança , Humanos , Hospedeiro Imunocomprometido , Interferon gama/biossíntese , Linfócitos T Auxiliares-Indutores/imunologiaRESUMO
Adenovirus infection after allogeneic hematopoietic stem cell transplantation is still causing significant morbidity and mortality, especially in children. It has been demonstrated that a sufficient host T-cell response is essential to clear the virus. Adoptive transfer of specific T-cell immunity from the donor to the recipient has become a new treatment option for patients with systemic adenoviral infection who lack specific T-cell responses. The adenoviral hexon protein was shown to be an immunodominant T-cell target. We describe here a Good Manufacturing Practice-compatible generation of hexon-specific T cells developed by isolating interferon-gamma-secreting T cells after stimulation of mononuclear cells ex vivo with hexon protein. Phenotypical and functional characterization of the generated, specific T-cell product resulted in a mixed population of CD4 and CD8-positive T cells with an intermediate effector memory phenotype. Isolated hexon-specific T cells showed high expansion potential in vitro and specific cytotoxicity. T-cell lines, directed against type 5 hexon protein showed good crossreactivity against viral strains from other adenovirus species. The availability for isolation of hexon-specific T cells among 76 hematopoietic stem cell transplantation donors showed in > 72% a sufficient T-cell response (0.05% of T cells). In conclusion, Good Manufacturing Practice-grade selection of adenovirus-specific T cells for adoptive immunotherapy by hexon-induced secretion of interferon-gamma has been established. Adoptive T-cell transfer could potentially restore T-cell immunity against adenovirus after allogeneic stem cell transplantation.