Impaired Alloantigen Presenting Activity of Cord Blood Nucleated Cells.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2203-2203
Author(s):  
Sandeep Chunduri ◽  
Dolores Mahmud ◽  
Javaneh Abbasian ◽  
Damiano Rondelli
Keyword(s):  
T Cells ◽  
Stem Cell ◽  
T Cell ◽  
Cord Blood ◽  
Mononuclear Cells ◽  
Ex Vivo ◽  
Solid Organ Transplantation ◽  
T Cell Response ◽  
Solid Organ ◽  
Cd34 Cells

Abstract Transplantation of HLA-mismatched cord blood (CB) nucleated cells has limited risk of severe acute graft-versus-host disease and graft rejection. This may depend on naïve T cells not yet exposed to many antigens and on immature antigen-presenting cells (APC) not delivering appropriate signals to allogeneic T cells. In order to test the APC activity of human circulating CB cells in-vitro, we initially used irradiated CB mononuclear cells (MNC) or immunomagnetically selected CD34+ cells, CD133+ cells, or CD14+ monocytes to stimulate the proliferative response of incompatible blood T cells in mixed leukocyte culture (MLC). CB MNC failed to induce allogeneic T cell proliferation, while CD34+ and CD133+ progenitors or CD14+ monocytes induced potent T cell alloresponses. Nevertheless, since allogeneic T cell response was not restored after depletion of CD3+ cells in the CB, nor the add-back of irradiated CB MNC to CD34+ or CD14+ stimulators inhibited allo-T cells, a direct suppressive effect of CB MNC was excluded. Allogeneic peripheral blood cytotoxic T-lymphocyte (CTL) responses were not induced after 7 days of stimulation with irradiated CB MNC, although after 4 weekly rechallenges with CB MNC, on average a 23% lysis of antigen-specific CB PHA-blasts was observed at the highest effector:target ratio (50:1). To test the tolerogenic potential of CB MNC, T cells initially exposed to CB MNC were rechallenged in secondary MLC with CB MNC, or CD34+ cells, or monocyte-derived dendritic cells (Mo-DC) generated in liquid culture with GM-CSF and IL-4. Allogeneic T cells were still unresponsive upon rechallenge with CB MNC, but proliferated upon 3 days of restimulation with CD34+ cells or Mo-DC from the same CB. Surprisingly, the supernatant of these latter MLCs did inhibit completely a 3rd party MLC. Instead, the supernatant of blood T cells that had been activated by CB CD34+ cells or Mo-DC both in primary and secondary MLC did not. These results show an impaired allo-APC activity of CB MNC but not CB CD34+ cells, and suggest that T cells releasing immunosuppressive cytokines may be activated by CB MNC and then expanded by a second more potent stimulation with professional APC. This hypothesis could explain the sustained engraftment of HLA-mismatched CB stem cell transplants in humans. Based on these results, the in-vivo or ex-vivo downregulation of T cell alloreactivity induced by CB MNC will be tested in experimental models of stem cell, as well as solid organ transplantation.

Patients (Pts) Surviving Haploidentical Stem Cell Transplantation (SCT) after Ex Vivo Costimulatory Blockade To Induce Anergy Experience Few Long-Term Complications.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 599-599 ◽  
Author(s):  
Eva C. Guinan ◽  
John G. Gribben ◽  
Lisa L. Brennan ◽  
Lee M. Nadler
Keyword(s):  
T Cells ◽  
Stem Cell ◽  
T Cell ◽  
Ex Vivo ◽  
Chronic Gvhd ◽  
T Cell Response ◽  
T Cell Repertoire ◽  
Cell Repertoire ◽  
Costimulatory Blockade ◽  
Cell Counts

Abstract Poor and delayed immune reconstitution remains a major stumbling block to successful SCT especially when alternative donors are used. Strategies to selectively remove or inactivate alloreactive cells while leaving the other donor T cell repertoire intact might address this problem. A functional T cell response requires an antigen (Ag)-specific MHC-restricted signal (signal 1) to the T cell receptor (TCR) by an Ag presenting cell (APC) as well as a second, Ag independent costimulatory signal (signal 2) provided in large part by B7 family members on APC to CD28 on T cells. Without signal 2, T cells develop tolerance to the specific Ag. Costimulation can be blocked by either CTLA4-Ig, a fusion of Ig with human CTLA4 (the T cell high affinity B7 ligand) or a combination of humanized IgG2 isotype mutated monoclonal antibodies to the APC molecules B7-1 and B7-2. In 2 pilot studies of patients (pts) undergoing haploidentical SCT, donor T cell replete BM was incubated ex vivo with recipient irradiated peripheral blood mononuclear cells with CTLA4-Ig (pilot 1) or anti-B7-1+anti-B7-2 (pilot 2) to induce alloAg specific tolerance. 19 pts age 7 mos-50 yrs (median 15 yrs) were enrolled on pilot 1 and 5 aged 4–12 (median 6) on pilot 2. 3 pts had congenital BM failure. 21 pts with malignancy, ALL (11), AML(7), NHL(2), MDS(1), were >CR1and 14/21 had progressive disease (PD). Pts received TBI based ablative conditioning. Pts received a median of 3.3x106/kg CD34+ cells (0.5–12.3) containing a median of 2.8x 107/kg CD3+ (0.7–6.8), 1.6x 107/kg CD4+ (0.4–4.1), and 1x107/kg CD8+ (0.2–3.7) T cells. One pt got additional anergized cells for slow recovery and engrafted fully. One AML pt had autologous persistence and graft failure (GF). Evaluable pts engrafted at median 21 d (range, 13–29) with full donor chimerism. Of the 21 evaluable pts, 9 (43%) had findings consistent with acute GVHD graded B (n=4), C (n=4) and D (n=1) despite inconsistent pathology. GVHD symptoms were largely isolated to the GI tract and resolved with observation or moderate steroids. No death was attributable to GVHD. 11 pts died early of a combination of bacterial or fungal infection and/or regimen-related toxicity at a median of 35 d (8–159). Of the remaining 13 pts, the GF pt died after 2nd SCT elsewhere, 1 pt had sudden death d 176 at home and 2 pts with extramedullary AML died d 60 and 149 with PD. One T-ALL pt died of late PD d 1758. All BM failure and 3/14 transplanted with PD survive. All 8 survivors (8/19 < 23 yrs) have 100% performance status at a median of 2423 d (1580–2875). None take medications or have chronic GVHD. 3 pts became CMV Ag + by d 100, (1 was transplanted with CMV), and responded to anti-viral therapy. Unlike many reported approaches to haploidentical SCT, aside from several CVL associated bacteremias, there have been no admissions for opportunistic infection and no late viral infections. All pts have good T cell counts, respond to vaccines and specific Ags and have good immunoglobulin levels. Costimulatory blockade, a method of limiting alloreactivity which leaves the remaining T cell repertoire intact, holds out promise as a method of overcoming alloreactivity while better preserving donor immune function and preserving anti-tumor activity. A new study combining costimulatory blockade and megadose stem cell SCT has been initiated.

scholarly journals Expansion of HIV-specific CD4+ and CD8+ T cells by dendritic cells transfected with mRNA encoding cytoplasm- or lysosome-targeted Nef

Blood ◽  
2006 ◽  
Vol 107 (5) ◽  
pp. 1963-1969 ◽  
Author(s):  
Daniel G. Kavanagh ◽  
Daniel E. Kaufmann ◽  
Sherzana Sunderji ◽  
Nicole Frahm ◽  
Sylvie Le Gall ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Mononuclear Cells ◽  
Ex Vivo ◽  
Cytotoxic T Cells ◽  
T Cell Response ◽  
Peripheral Blood Mononuclear ◽  
T Cell Lines

Transfection with synthetic mRNA is a safe and efficient method of delivering antigens to dendritic cells for immunotherapy. Targeting antigens to the lysosome can sometimes enhance the CD4+ T-cell response. We transfected antigen-presenting cells (APCs) with mRNA encoding Gag-p24 and cytoplasmic, lysosomal, and secreted forms of Nef. Antigen-specific cytotoxic T cells were able to lyse the majority of transfected targets, indicating that transfection was efficient. Transfection of APCs with a Nef construct bearing lysosomal targeting signals produced rapid and prolonged antigen presentation to CD4+ and CD8+ T cells. Polyclonal CD4+ and CD8+ T-cell lines recognizing multiple distinct epitopes were expanded by coculture of transfected dendritic cells with peripheral blood mononuclear cells from viremic and aviremic HIV-infected subjects. Importantly, lysosome-targeted antigen drove a significantly greater expansion of Nef-specific CD4+ T cells than cytoplasmic antigen. The frequency of recognition of CD8 but not CD4 epitopes by mRNA-expanded T cells was inversely proportional to sequence entropy and was similar to ex vivo responses from a large chronic cohort. Thus human dendritic cells transfected with mRNA encoding lysosome-targeted HIV antigen can expand a broad, polyclonal repertoire of antiviral T cells, offering a promising approach to HIV immunotherapy.

Cord Blood Nucleated Cells Induce Delayed Proliferative and Cytotoxic T Cell Alloreactivity.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 5138-5138
Author(s):  
Dolores Mahmud ◽  
Sandeep Chunduri ◽  
Javaneh Abbasian ◽  
John Maciejewski ◽  
Ronak Iqbal ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Cord Blood ◽  
T Cell Response ◽  
Cytotoxic T Cell ◽  
T Cell Proliferation ◽  
Cd34 Cells ◽  
Ctl Activity

Abstract Transplantation of HLA-mismatched nucleated cells from cord blood (CB) has reduced risks of graft rejection and severe acute graft-versus-host disease. In this study we analyzed the in-vitro alloantigen presenting capacity of cord blood nucleated cells. CB mononuclear cells (MNCs) or immunomagnetically-selected CD34+ cells, or CD14+ monocytes, were irradiated and tested as stimulators of allogeneic blood T cells in primary (stimulator:responder ratio = 1:1) or secondary (stimulator:responder ratio = 1:2) mixed leukocyte culture (MLC), or in cytotoxic T-lymphocytes (CTL) assays. CB-MNCs failed to induce allogeneic T cell proliferation in 6-days primary MLC, whereas CD34+ or CD14+ cells stimulated brisk T cell responses. A suppressive effect of CB-MNCs was ruled out since CD3+ cell-depletion of CB-MNCs did not restore CB immunogenicity and the addition of increasing doses of CB-MNCs did not inhibit T cell alloreactivity to CD34+ cells. Despite allogeneic T cells were unresponsive to CB-MNCs after primary and secondary MLC, T cell anergy was ruled out since T cells that were unresponsive after primary MLC proliferated potently in secondary MLC stimulated with CB CD34+ cells, and even more with CB monocyte-derived dendritic cells (Mo-DC) generated in-vitro with GM-CSF and IL-4. Interestingly, after co-culture with irradiated allogeneic T cells for 6 days, CB-MNCs showed a greater proportion of CD86+ cells and elicited allo- T cell proliferation. In addition, allo-CTL activity was induced by CB-MNCs only after restimulating effector cells for 3–4 weeks (26±7% lysis of antigen-specific PHA-blast at 50:1 E:T ratio), and was comparable to CTL activity induced after 1 week by Mo-DC generated from the same CB. When T cell effectors were stimulated by combining two incompatible cord blood MNCs mixed together, CTL activity was then detected after 4 weeks against both of them regardless of the CB:CB cell ratio. These results show an impaired allo-APC activity of CB-MNCs, without suppressive or tolerogenic activity. These findings might partially explain the initial engraftment of combined HLA mismatched CB grafts in vivo, however they also suggest that a delayed T cell response may occur due to CB-derived APCs activating CTLs.

scholarly journals Broad and Efficient Activation of Memory CD4+ T Cells by Novel HAdV- and HCMV-Derived Peptide Pools

2021 ◽  
Vol 12 ◽  
Author(s):  
Alexander Höttler ◽  
Léo März ◽  
Maren Lübke ◽  
Hans-Georg Rammensee ◽  
Stefan Stevanović
Keyword(s):  
T Cells ◽  
T Cell ◽  
Intracellular Cytokine Staining ◽  
Solid Organ Transplantation ◽  
T Cell Response ◽  
High Morbidity ◽  
Solid Organ ◽  
Immunocompromised Patients ◽  
T Cell Epitopes ◽  
Peripheral Blood Mononuclear

Reactivation of Human Cytomegalovirus (HCMV) and Human Adenovirus (HAdV) in immunocompromised patients following stem cell transplantation (SCT) or solid organ transplantation (SOT) is associated with high morbidity and mortality. The adoptive transfer of virus-specific CD8+ and CD4+ T cells has been shown to re-establish the antiviral T-cell response and improve clinical outcome. The viral load in immunocompromised patients can efficiently be reduced solely by the infusion of virus-specific CD4+ T cells. The identification of CD4+ T-cell epitopes has mainly focused on a limited number of viral proteins that were characterized as immunodominant. Here, we used in silico prediction to determine promiscuous CD4+ T-cell epitopes from the entire proteomes of HCMV and HAdV. Immunogenicity testing with enzyme-linked immuno spot (ELISpot) assays and intracellular cytokine staining (ICS) revealed numerous novel CD4+ T-cell epitopes derived from a broad spectrum of viral antigens. We identified 17 novel HCMV-derived and seven novel HAdV-derived CD4+ T-cell epitopes that were recognized by > 50% of the assessed peripheral blood mononuclear cell (PBMC) samples. The newly identified epitopes were pooled with previously published, retested epitopes to stimulate virus-specific memory T cells in PBMCs from numerous randomly selected blood donors. Our peptide pools induced strong IFNγ secretion in 46 out of 48 (HCMV) and 31 out of 31 (HAdV) PBMC cultures. In conclusion, we applied an efficient method to screen large viral proteomes for promiscuous CD4+ T-cell epitopes to improve the detection and isolation of virus-specific T cells in a clinical setting.

scholarly journals Determining the Quantitative Principles of T Cell Response to Antigenic Disparity: The Case of Stem Cell Transplant Donor-Recipient Exome Wide Mismatching and HLA Bound Alloreactive Peptides

2018 ◽  
Author(s):  
Ali Salman ◽  
Vishal Koparde ◽  
Charles Hall ◽  
Max Jameson-Lee ◽  
Catherine Roberts ◽  
...  
Keyword(s):  
Stem Cell ◽  
T Cell ◽  
Binding Affinity ◽  
Cell Response ◽  
Solid Organ Transplantation ◽  
Hla Class I ◽  
T Cell Response ◽  
Class I ◽  
Solid Organ ◽  
Cell Transplant

AbstractAlloreactivity compromising clinical outcomes in stem cell transplantation is observed despite HLA matching of donors and recipients. This has its origin in the variation between the exomes of the two, which provides the basis for minor histocompatibility antigens (mHA). The mHA presented on the HLA class I and II molecules and the ensuing T cell response to these antigens results in graft versus host disease. In this paper, results of a whole exome sequencing study are presented, with resulting alloreactive polymorphic peptides and their HLA class I and HLA class II (DRB1) binding affinity quantified. Large libraries of potentially alloreactive recipient peptides binding both sets of molecules were identified, with HLA-DRB1 presenting an order of magnitude greater number of peptides. These results are used to develop a quantitative framework to understand the immunobiology of transplantation. A tensor-based approach is used to derive the equations needed to determine the alloreactive donor T cell response from the mHA-HLA binding affinity and protein expression data. This approach may be used in future studies to simulate the magnitude of expected donor T cell response and risk for alloreactive complications in HLA matched or mismatched hematopoietic cell and solid organ transplantation.

Anti-CD3 Activated T Cells from Cord Blood Can Be Expanded Ex Vivo and Armed with Bispecific Antibodies To Lyse Her2/Neu + and CD20+ Targets: A Strategy for Providing Anti-Tumor/Lymphoma Effects after Cord Blood Transplant.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2751-2751
Author(s):  
Carly B. Sorenson ◽  
Thomas D. Frandsen ◽  
Suanne Dorr ◽  
Voravit Ratanatharathorn ◽  
Joseph P. Uberti ◽  
...  
Keyword(s):  
T Cells ◽  
Stem Cell ◽  
Cord Blood ◽  
Mononuclear Cells ◽  
Ex Vivo ◽  
Interleukin 2 ◽  
Cell Transplant ◽  
Activated T Cells ◽  
Specific Cytotoxicity ◽  
The Mean

Abstract Our previous studies showed that anti-CD3 activated T cells (ATC) from peripheral blood mononuclear cells could be expanded in interleukin-2 (IL-2) for 14 days and armed with anti-CD3 x anti-Her2/neu (Her2Bi)[J Hemat & Stem Cell Res10:247,2001], anti-CD3 x anti-CD20 (CD20Bi)[Exp Hemat33:452,2005], or anti-CD3 x anti-EGFR [Clin Cancer Res12:183,2006] bispecific antibody (BiAb)and can kill Her2/neu, CD20, and EGFR+ tumor targets, respectively. In this study, we asked whether anti-CD3 activated cord blood T cells (CBATC) could be expanded and targeted with Her2Bi and CD20Bi to tumors or hematologic malignancies for infusions after cord blood stem cell transplant (CBSCT). CB mononuclear cells were activated with anti-CD3 (20 ng/ml) and expanded for 14 days in IL-2 (100 IU/ml). CBATC were armed with Her2Bi or CD20Bi and tested for specific cytotoxicity directed SK-BR-3, Raji, or B9C targets and cytokine secretion or IFNγ EliSpots after binding to tumor cells. Our results show the mean expansion of CBATC to be 43-fold (n=8) after 14 days of culture. By the end of culture, the proportions of CD8+ and CD4+ were 82% and 18%, respectively. The proportion of cells expressing CD19 or CD20 did not exceed 6.3%, CD56+ cells were <3.6% and CD3-CD16+CD56+ cells was <0.7%. Cells positive for CD4+CD25+ or CD8+ CD25+ were 4.2% or 7.1%, respectively (n=2). Specific cytotoxicity was optimized when CBATC were armed with 50 ng/106 cells of Her2Bi or CD20Bi (arming dose ranged from 5, 50, and 500 ng/106 cells); arming significantly increased cytotoxicity of the armed CBATC over that seen for unarmed CBATC. Cytotoxicity peaked between days 12 and 14 for both BiAbs. The ability of CD20Bi armed ATC to produce Elispots for IFNγ were tested by arming ATC the CD20Bi after 0, 8, 11, and 13 days of culture peaked on day 8. Only CD20+ targets induced Elispots and day 8 armed ATC exhibited peak numbers (2,200 Elispots(ranged from 1,700 to 1,800 on day 8)/106 armed ATC plated). At an effector/target ratio (E:T) of 25:1, the mean cytotoxicity of CBATC armed with Her2Bi or CD20Bi was 60% (n=4) and 35% (n=1), respectively. In an extended culture to day 47, mean cytotoxicity for Her2Bi-armed CBATC was 36% at an E/T of 25:1 compared to 4.35% for unarmed CBATC. Unarmed CBATC did not kill Daudi targets. Armed CBATC mediated both specific cytotoxicity and secreted IFN-γ as measured by ELISA or EliSpots. Both fresh and frozen CB could be used in the assays. In a clinical application, specific cytotoxicity of armed CBATC could be used to augment anti-tumor and anti-lymphoma effects after CBSCT.

Expression of RHAMM and WT1 As Well As T Cell Responses to These Antigens Before and After Allogeneic Stem Cell Transplantation in Patients with Leukemia

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 4315-4315
Author(s):  
Rosaely Casalegno-Garduño ◽  
Claudia Meier ◽  
Jiju Mani ◽  
Kersten Borchert ◽  
Inken Hilgendorf ◽  
...  
Keyword(s):  
T Cells ◽  
Stem Cell ◽  
T Cell ◽  
Complete Remission ◽  
Stem Cell Transplantation ◽  
Mononuclear Cells ◽  
T Cell Responses ◽  
T Cell Response ◽  
Cell Responses ◽  
Before And After

Abstract Abstract 4315 Introduction: Patients with leukemia undergo chemotherapy as first treatment. Approximately 70–80% of patients with acute myeloid leukemia (AML) reach complete remission. However, most of them will relapse and only 25% survive more than five years. Therefore, there is a need for novel approaches in the treatment of leukemia, such as immunotherapy. Leukemic blasts have an aberrant expression of antigens. They are called leukemia-associated antigens (LAAs) like the receptor for hyaluronan acid-mediated motility (RHAMM) and the Wilms’ tumor gene 1 product (WT1). Epitopes of these LAAs can be recognized by CD8+ T cells. MATERIAL AND METHODS: In the present study, we analyzed the correlation between the clinical course of 18 patients suffering from leukemia (10 AML, 5 MDS, 1 ALL and 2 B-CLL) with the expression of RHAMM and WT1 transcripts before and after allogeneic stem cell transplantation (allo-SCT). Gene transcripts were measured by quantitative real time PCR (RQ-PCR) from RNA of peripheral blood mononuclear cells (PBMC) and bone marrow mononuclear cells (BMMC) samples. Antigen specific T cells were enriched in a mixed lymphocyte-peptide culture (MLPC) and antigen specific T cell responses were measured by enzyme-linked immunosorbent spot (ELISPOT). Results: We observed a reduction in WT1 transcripts in both PBMC and BMMC after transplantation in all of the WT1 positive patients (6/18 patients: 33%). Four of these six WT1+ patients (67%) remained in complete remission (CR) with low transcripts of WT1 (PBMC: lower than 14 WT1 copies/104 ABL copies, BMMC: lower than 202 WT1 copies/104 ABL copies). In contrast, 2 of 6 WT1+ patients (33%) showed an increase (PBMC: up to 98 WT1 copies/104 ABL copies, BMMC: up to 920 WT1 copies/104 ABL copies) of WT1 transcripts eventually resulting in a relapse. Specific T cell responses were detected against WT1 in two of three WT1+ patients in the presence of blasts (before transplantation or in relapse). However, these specific responses vanished while the patients reached a CR. Furthermore, RHAMM+ patients (12/18: 67%) showed different patterns when correlated with clinical status. Five patients (42%) showed gradually increased levels of RHAMM transcripts during CR. No RHAMM specific T cells could be detected in this group (2/2 MLPCs). Four patients (33%) showed a decrease in the transcripts of RHAMM when they reached a CR. One of these patients developed a T cell response to RHAMM three months after allo-SCT (2/2 MLPCs). One patient showed high transcripts of RHAMM and WT1 during the diagnosis, WT1 transcripts were reduced after allo-SCT. Both RHAMM and WT1 transcripts gradually increased until the patients died. We could detect in this patient both WT1 and RHAMM-specific T cells before transplantation. After allo-SCT the T cell response vanished. CONCLUSION: Taken together, WT1 is a suitable marker for minimal residual disease after allo-SCT. One might speculate that T cells specific for WT1 vanished during the CR due to the absence of the antigen to stimulate the proliferation of specific T cell population. Moreover, the presence of RHAMM-specific T cells may help to maintain a CR. In both cases vaccination with RHAMM and WT1 derived peptide might enhance T cell responses in the patient leading to a better outcome of the patient. Disclosures: Freund: Medac: Honoraria, Research Funding.

scholarly journals Symptomatic and Asymptomatic Viral Recrudescence in Solid-Organ Transplant Recipients and Its Relationship with the Antigen-Specific CD8+ T-Cell Response

2007 ◽  
Vol 81 (20) ◽  
pp. 11538-11542 ◽  
Author(s):  
Tania Crough ◽  
Chrysa Fazou ◽  
Julissa Weiss ◽  
Scott Campbell ◽  
Miles P. Davenport ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Response ◽  
Ex Vivo ◽  
Organ Transplant ◽  
Hla Class I ◽  
T Cell Response ◽  
Solid Organ ◽  
Transplant Recipients ◽  
Ifn Γ

ABSTRACT Using ex vivo antigen-specific T-cell analysis, we found that symptomatic cytomegalovirus recrudescence in transplant recipients was coincident with reduced expression of gamma interferon (IFN-γ) by virus-specific CD8+ T cells and an up-regulation of CD38 expression on these T cells, although there was no significant change in the absolute number of virus-specific cells (as assessed by major histocompatibility complex-peptide multimers). In contrast, HLA class I-matched transplant patients with asymptomatic viral recrudescence showed increased expansion of antigen-specific T cells and highly stable IFN-γ expression by epitope-specific T cells. These studies suggest that a strong functional T-cell response plays a crucial role in defining the clinical outcome of acute viral recrudescence.

scholarly journals Tracking of Peptide-Specific CD4+ T-Cell Responses after an Acute Resolving Viral Infection: a Study of Parvovirus B19

2006 ◽  
Vol 80 (22) ◽  
pp. 11209-11217 ◽  
Author(s):  
Victoria Kasprowicz ◽  
Adiba Isa ◽  
Thomas Tolfvenstam ◽  
Katie Jeffery ◽  
Paul Bowness ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mononuclear Cells ◽  
Ex Vivo ◽  
Parvovirus B19 ◽  
Acute Infection ◽  
T Cell Responses ◽  
T Cell Response ◽  
Immunoglobulin M ◽  
Cell Responses

ABSTRACT The evolution of peptide-specific CD4+ T-cell responses to acute viral infections of humans is poorly understood. We analyzed the response to parvovirus B19 (B19), a ubiquitous and clinically significant pathogen with a compact and conserved genome. The magnitude and breadth of the CD4+ T-cell response to the two B19 capsid proteins were investigated using a set of overlapping peptides and gamma interferon-specific enzyme-linked immunospot assays of peripheral blood mononuclear cells (PBMCs) from a cohort of acutely infected individuals who presented with acute arthropathy. These were compared to those for a cohort of B19-specific immunoglobulin M-negative (IgM−), IgG+ remotely infected individuals. Both cohorts of individuals were found to make broad CD4+ responses. However, while the responses following acute infection were detectable ex vivo, responses in remotely infected individuals were only detected after culture. One epitope (LASEESAFYVLEHSSFQLLG) was consistently targeted by both acutely (10/12) and remotely (6/7) infected individuals. This epitope was DRB1*1501 restricted, and a major histocompatibility complex peptide tetramer stained PBMCs from acutely infected individuals in the range of 0.003 to 0.042% of CD4+ T cells. Tetramer-positive populations were initially CD62Llo; unlike the case for B19-specific CD8+ T-cell responses, however, CD62L was reexpressed at later times, as responses remained stable or declined slowly. This first identification of B19 CD4+ T-cell epitopes, including a key immunodominant peptide, provides the tools to investigate the breadth, frequency, and functions of cellular responses to this virus in a range of specific clinical settings and gives an important reference point for analysis of peptide-specific CD4+ T cells during acute and persistent virus infections of humans.

Degranulation of T-Cells Specific for the CMV-Proteins pp65 and IE-1 in Allogeneic Stem Cell Recipients.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 5136-5136
Author(s):  
Susanne S. Ganepola ◽  
Stephan S. Fuhrmann ◽  
Lutz L. Uharek ◽  
Eckhard E. Thiel ◽  
Hans Dieter H.D. Volk ◽  
...  
Keyword(s):  
T Cells ◽  
Stem Cell ◽  
T Cell ◽  
Cytokine Production ◽  
Cell Function ◽  
Conditioning Regimen ◽  
Solid Organ Transplantation ◽  
Solid Organ ◽  
Cmv Antigenemia ◽  
Ctl Activity

Abstract Infection and disease with human cytomegalovirus (HCMV) is still an important cause for morbidity and mortality after allogeneic stem cell transplantation (allo SCT). Specific T-cells (CTL) are crucial for the control of CMV infection. In addition to cytokine production, degranulation is an interesting marker of T-cell function. Recent studies in patients after solid organ transplantation revealed that high levels of IE-1-specific CTL correlate with a protection from CMV disease. However, the functionality of these cells is less clear. As demonstrated in AIDS suffering patients, CTL activity is more related to a protection than to a cytokine secretion. Here we address the question, whether CD4 and CD8 T-cells have different abilities to degranulate or to produce cytokines depending on the type of immunosuppression and the CMV target protein. Material and Methods: T-cells from 6 healthy CMV exposed donors and 16 allografted patients (11 AML, 3 ALL, 1 NHL, 1 MPS) were stimulated with peptide pools representing the pp65 (UL83) and IE-1 (UL123) proteins. Mobilized CD107 (marker of CTL activity), TNF, IFN-g, and IL-2 production was analyzed by 8-color flowcytometry. Immunosuppression consisted of CSA/MMF (n=4), CSA alone (n=4) and CSA/MTX (n=8), 4/8 patients additionally received ATG for GvHD-prophylaxis as part of the conditioning regimen. In all transplanted patients CMV antigenemia was assessed twice a week. Results and Conclusion: The responding T-cell population mainly demonstrated an effector phenotype with a low expression of CD28. Frequency of reactive CTL did not correlate with CMV antigenemia. Interestingly, there was no impairment of degranulation or cytokine production found in any of the allogeneic transplanted patients compared with healthy CMV exposed controls, showing that immunosuppression does not target the function of the specific CTL.

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