Rapid monitoring of immune reconstitution after allogeneic stem cell transplantation--a comparison of different assays for the detection of cytomegalovirus-specific T cells.

Cytotoxic T cells (CTLs) play an important role in controlling cytomegalovirus (CMV) infection after allogeneic hematopoietic stem cell transplantation (HSCT). The purpose of this study was to compare four different assays to detect CMV antigen-specific T cells for the monitoring of CMV-specific immune reconstitution after HSCT. Comparative monitoring of CMV-specific T cells was performed using HLA tetramer, interferon-gamma enzyme-linked immunospot (ELISPOT), intracellular IFN-γ (IC-FACS), and real-time polymerase chain reaction (RT-PCR) assays with immunodominant CMV pp65-HLA-A2-restricted peptide and recombinant pp65-protein in 18 patients after allogeneic HSCT. Using pp65-peptide to stimulate T cells in HLA-A2-positive patients, antigen-specific T cells have been detected in 43% (10 of 23) by IC-FACS, 62% (13 of 21) by tetramer, 68% (15 of 22) by RT-PCR, and 53% (10 of 19) by ELISPOT. No T-cell responses were detected in HLA-A2-negative patients by all assays. Stimulating with combination of both pp65-peptide and pp65-protein detected 72% (18/25) by IC-FACS, 88% (22/25) by RT-PCR, and 59% (12/22) by ELISPOT. Comparing the different methods of T-cell detection we found a significant positive correlation between RT-PCR and tetramer analysis, IC flow cytometry and ELISPOT assay. Using pp65-protein for T-cell activation overcomes the HLA restriction of the HLA-A2-restricted pp65-peptide stimulation, thus increasing the detection limit of antigen-specific T cells. CMV-specific T cells have been most frequently detected using RT-PCR suggesting a higher sensitivity compared with IC-FACS, tetramer, and ELISPOT assays. This technique allows rapid and sensitive monitoring of CMV-specific immune reconstitution after HSCT, which could guide prophylactic and therapeutic strategies to avoid active CMV disease.

Abu-Khader A ，Krause S 《-》

Evaluation of cytomegalovirus-specific T-cell reconstitution in patients after various allogeneic haematopoietic stem cell transplantation using interferon-gamma-enzyme-linked immunospot and human leucocyte antigen tetramer assays with an immunodominant T

Ohnishi M ，Sakurai T ，Heike Y ，Yamazaki R ，Kanda Y ，Takaue Y ，Mizoguchi H ，Kawakami Y ... -  《BRITISH JOURNAL OF HAEMATOLOGY》

Evaluation of suitable target antigens and immunoassays for high-accuracy immune monitoring of cytomegalovirus and Epstein-Barr virus-specific T cells as targets of interest in immunotherapeutic approaches.

Adoptive immunotherapy with donor-derived antiviral T cells can prevent viral complications such as with cytomegalovirus (CMV) and Epstein-Barr virus (EBV). In this context accurate monitoring of cellular immunity is essential and requires suitable quantitative and qualitative assays for high-throughput screening. We comparatively analyzed 57 HLA-typed healthy donors for memory T-cell responses to CMV- and EBV-derived proteins, peptide pools and single HLA-restricted peptides by five commonly used immunoassays in parallel: enzyme-linked immunospot (ELISPOT), cytokine secretion assay (CSA), intracellular cytokine staining (ICS), enzyme-linked immunosorbent assay (ELISA) and pMHC multimer staining. T-cell responses varied greatly between the different target antigens in the investigated assays. IFN-γ ELISPOT consistently detected the highest T-cell response levels against CMV and EBV. CMV-specific T cells were detected in 100% of CMV-seropositive donors tested using CMVpp65 protein and/or overlapping CMVpp65 peptide pool. CMV-specific T cells in HLA-A*02:01-positive/CMV-seropositive donors were identified directly by HLA-A02/CMVpp65 (A02pp65) multimer staining and, after short in vitro stimulation with HLA-A*02:01-restricted pp65 peptide, by ELISPOT, ELISA, ICS and CSA. A peptide-specific T-cell response was detected in only 4 HLA-A*02:01-positive donors (50%). Despite A02pp65 peptide negativity, T-cell responses to CMVpp65 protein and/or overlapping peptide pool were detected. Comparing the specific immune response against EBV antigens in healthy donors overall, BZLF1-specific T cells (<92.9% peptides, <56.3% peptide pool) were more frequent than EBNA-specific T cells (<64.3% peptides, <46.9% peptide pool) with higher percentage of positive findings for single HLA-restricted EBV peptides. T-cell response against HLA-B*08 peptide epitopes was predominant (multimer staining: EBNA3A: 9/14 and BZLF1: 7/14, IFN-γ ELISPOT: EBNA3A: 13/14 and BZLF1: 11/14). The fact that responses to EBV-specific antigens were not detected in every single EBV-seropositive donor as well as that the T-cell frequencies in response to the investigated EBV antigens differed strongly in the donor cohort indicates that these epitopes are less immunodominant than CMVpp65. Taken together, precise monitoring of T-cell immunity against infectious agents in potential T-cell donors and post-transplant recipients requires individual selection of antigens and immunoassays for the efficient detection and generation of clinically relevant T cells. Due to its lower detection limit and direct visualization of each IFN-γ-secreting cell we identified ELISPOT analysis to be preferable for high-throughput pre-screening. CSA was found to be advantageous for a more detailed analysis of antigen-specific T-cell subsets.

Tischer S ，Dieks D ，Sukdolak C ，Bunse C ，Figueiredo C ，Immenschuh S ，Borchers S ，Stripecke R ，Maecker-Kolhoff B ，Blasczyk R ，Eiz-Vesper B ... -  《-》

Cytomegalovirus immune reconstitution occurs in recipients of allogeneic hematopoietic cell transplants irrespective of detectable cytomegalovirus infection.

Gallez-Hawkins G ，Thao L ，Lacey SF ，Martinez J ，Li X ，Franck AE ，Lomeli NA ，Longmate J ，Diamond DJ ，Spielberger R ，Forman SJ ，Zaia JA ... -  《BIOLOGY OF BLOOD AND MARROW TRANSPLANTATION》

Soluble recombinant CMVpp65 spanning multiple HLA alleles for reconstitution of antiviral CD4+ and CD8+ T-cell responses after allogeneic stem cell transplantation.

Paine A ，Oelke M ，Tischer S ，Heuft HG ，Blasczyk R ，Eiz-Vesper B ... -  《-》