scholarly journals Major histocompatibility complex-expressing nonhematopoietic astroglial cells prime only CD8+ T lymphocytes: astroglial cells as perpetuators but not initiators of CD4+ T cell responses in the central nervous system.

1991 ◽  
Vol 173 (5) ◽  
pp. 1235-1246 ◽  
Author(s):  
J D Sedgwick ◽  
R Mössner ◽  
S Schwender ◽  
V ter Meulen
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mhc Class I ◽  
Cd8 T Cells ◽  
T Cell Responses ◽  
Cd4 T Cell ◽  
Astroglial Cells ◽  
Cell Responses ◽  
Histocompatibility Complex ◽  
The Central Nervous System

The potential of cells within the central nervous system (CNS) to initiate T lymphocyte responses is not known and was the subject of this study. Using the ability of virgin T lymphocytes to proliferate in a primary response to allogeneic determinants on antigen-presenting cells (APC), we have examined the capacity of major histocompatibility complex (MHC)-expressing astroglial cells to act as stimulators of primary and secondary T cell responses. Neither freshly isolated astrocytes nor primary astrocyte cultures pretreated with interferon gamma (IFN-gamma) to upregulate MHC class I and II expression stimulated unfractionated lymph node (LN) cell populations in the primary mixed lymphocyte reaction. In mixing experiments, astrocytes did not inhibit the T cell response to allogeneic LN stimulators. Purified responder CD4+ T cells also were not stimulated to proliferate or secrete interleukin 2 (IL-2) by MHC class I- and II-expressing astrocytes. In contrast to their inability to stimulate virgin, alloreactive CD4+ T cells, astrocytes were able to specifically stimulate an alloreactive CD4+ T cell line. Unprimed CD8+ T cells, however, exhibited some weak autonomous proliferation to astrocyte stimulators but this response was only substantial in the presence of exogenous IL-2, the latter predominantly being a CD4+ T cell product. Those CD8+ T cells responding in the presence of IL-2 were mainly T cell receptor alpha/beta+ IL-2 receptor (alpha chain)+, and a majority had shifted from high to low CD45R expression. Given the virtual dependence of CD8+ T cells in these studies, on CD4+ T cell help, and the complete absence of activation of this latter subset by astrocytes, it is clear that in the context of this resident CNS cell, further activation of either T cell subset by astrocytes within the CNS can only follow priming by another type of APC. The implications of these results for the induction of T cell responses in the CNS are discussed.

scholarly journals Single cell profiling of T and B cell repertoires following SARS-CoV-2 mRNA vaccine

2021 ◽  
Author(s):  
Suhas Sureshchandra ◽  
Sloan A. Lewis ◽  
Brianna Doratt ◽  
Allen Jankeel ◽  
Izabela Ibraim ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cell ◽  
Single Cell ◽  
Cd8 T Cells ◽  
Natural Infection ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Cd4 T Cell ◽  
Cell Responses

mRNA based vaccines for SARS-CoV-2 have shown exceptional clinical efficacy providing robust protection against severe disease. However, our understanding of transcriptional and repertoire changes following full vaccination remains incomplete. We used single-cell RNA sequencing and functional assays to compare humoral and cellular responses to two doses of mRNA vaccine with responses observed in convalescent individuals with asymptomatic disease. Our analyses revealed enrichment of spike-specific B cells, activated CD4 T cells, and robust antigen-specific polyfunctional CD4 T cell responses in all vaccinees. On the other hand, CD8 T cell responses were both weak and variable. Interestingly, clonally expanded CD8 T cells were observed in every vaccinee, as observed following natural infection. TCR gene usage, however, was variable, reflecting the diversity of repertoires and MHC polymorphism in the human population. Natural infection induced expansion of larger CD8 T cell clones occupied distinct clusters, likely due to the recognition of a broader set of viral epitopes presented by the virus not seen in the mRNA vaccine. Our study highlights a coordinated adaptive immune response where early CD4 T cell responses facilitate the development of the B cell response and substantial expansion of effector CD8 T cells, together capable of contributing to future recall responses.

Spontaneous CD4 and CD8 Memory T Cell Responses Against MUC1 and Carcinoembryonic Antigen in Bone Marrow of Multiple Myeloma Patients.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3533-3533
Author(s):  
Mathias Witzens-Harig ◽  
Dirk Hose ◽  
Michael Hundemer ◽  
Simone Juenger ◽  
Anthony D. Ho ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
Carcinoembryonic Antigen ◽  
Cd8 T Cells ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Cd4 T Cell ◽  
Cell Responses

Abstract Introduction: The bone marrow (BM) is a site of induction of tumour antigen specific T cell responses in many malignancies. We have demonstrated in the BM of myeloma patients high frequencies of spontaneously generated CD8 memory T cells with specificity for the myeloma-associated antigen MUC1, which were not detectable in the peripheral blood (PB). Besides MUC1, carcinoembryonic antigen was recently identified as a tumour-associated antigen in a patient with multiple myeloma. Up to now, spontaneous CD4 T cell responses against myeloma-associated antigens have not been reported. We undertook this study to evaluate to what extent spontaneous CD4 T cell responses against myeloma antigens occur during myeloma progression and if MUC1 or carcinoembryonic antigen represent immunogenic targets of spontaneous CD4 and CD8 T cell responses. Methods: Altogether, 78 patients with multiple myeloma were included into the study. Presence of functionally competent antigen specific T cells was evaluated by ex vivo short term (40 h) IFN-γ Elispot analyses. CD4 T cell responses against MUC1 were assessed by stimulation of purified CD4 T cell fractions with antigen pulsed, autologous dendritic cells (DCs) pulsed with two synthetic 100 meric polypeptides (pp1-100ss and (137–157)5 tr) that can be processed and presented via multiple HLA-II alleles. CD4- or CD8 T cell reactivity against carcinoembryonic antigen was assessed on purified CD4- and CD8 T cell fractions by pulsing DCs with highly purified CEA derived from culture supernatants of an epithelial carcinoma cell line. CD8 responses against MUC1 were analyzed by stimulation of HLA-A2+ patients derived purified T cells with DCs loaded with HLA-A2 restricted MUC1-derived nonameric peptide LLLLTVLTV. As negative control antigen for MUC1 polypeptides and CEA human IgG was used for pulsing DCs at identical concentrations while HLA-A2-restricted peptide SLYNTVATL derived from HIV was used as control antigen for LLLLTVLTV. Test antigen specific reactivity was defined by significantly increased numbers of IFN-γ spots in triplicate test wells compared to control wells (p<0.05, students T test). Results: 8 out of 19 tested patients (42%) contained MUC1 specific CD8 T cells in their bone marrow, while MUC1 specific CD4 T cells were detected in the BM of 30% of the cases (3/10). Interestingly, in peripheral blood (PB) CD8 reactivity against MUC1 was detectable in only 1 out of 10 patients while CD4 reactivity in PB was not detectable at all (0/10). CEA was specifically recognized by BM CD8 T cells from 5 out of 30 patients (17%) and by BM CD4 T cells from 5 out of 18 patients (28%). CEA was not recognized by CD4 and CD8 T cells in the PB of the same patients (0/13). Conclusion: Spontaneous T helper responses against tumour-associated antigens occur in the BM at similar levels as antigen specific CD8 T cells responses while they are virtually undetectable in the PB. Compared to CEA, MUC1 induces CD8 T cell responses in a much higher proportion of myeloma patients. Nevertheless, our data suggest that CEA may trigger spontaneous T cell responses against multiple myeloma in a considerable number of patients. Thus, systematic functional analyses of this potential tumour antigen in multiple myeloma appears to be justified.

scholarly journals Conditional silencing of H-2Dbclass I molecule expression on dendritic cells modulates the protective and pathogenic kinetics of virus-antigen specific CD8 T cell responses during Theiler’s Virus infection

2019 ◽  
Author(s):  
Zachariah P. Tritz ◽  
Robin C. Orozco ◽  
Courtney S. Malo ◽  
Lila T Yokanovich ◽  
Katayoun Ayasoufi ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Antigen Presentation ◽  
Mhc Class I ◽  
Cd8 T Cells ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Class I ◽  
Viral Control ◽  
Cell Responses

ABSTRACTTheiler’s murine encephalomyelitis virus (TMEV) infection of the central nervous system is rapidly cleared in C57BL/6 mice by an anti-viral CD8 T cell response restricted by the MHC class I molecule, H-2Db. While the CD8 T cell response against neurotropic viruses is well characterized, the identity and function of the antigen presenting cell(s) involved in this process is(are) less well defined. To address this gap in knowledge, we developed a novel C57BL/6 H-2Dbconditional knockout mouse that expresses an H-2Dbtransgene in which the transmembrane domain locus is flanked by LoxP sites. We crossed these H-2DbLoxP mice with MHC class I-deficient mice expressing Cre-recombinase under either the CD11c or LysM promoter in order to silence H-2Dbrestricted antigen presentation predominantly in dendritic cells or macrophages, respectively. Upon challenge with intracranial TMEV infection, we observe that CD11c+ APCs are critical for early priming of CD8 T cells against the immunodominant TMEV peptide VP2121-130 presented in the context of the H-2Dbmolecule. This stands in stark contrast to later time points post TMEV infection where CD11c+ APCs appear dispensable for the activation of antigen-specific T cells; the functionality of these late-arising antiviral CD8 T cells is reflected in the restoration of viral control at later time points. These late-arising CD8 T cells also retain their capacity to induce blood-brain barrier disruption. In contrast, when H-2Dbrestricted antigen presentation was selectively silenced in LysM+ APCs there was no overt impact on the priming of Db:VP2121-130 epitope-specific CD8 T cells, although a modest reduction in immune cell entry into the CNS was observed. This work establishes a model system which enables critical dissection of MHC class I restricted antigen presentation to T cells, revealing cell specific and temporal features involved in the generation of antiviral CD8 T cell responses. Employing this novel system, we established CD11c+ cells as a pivotal driver of acute, but not later-arising, antiviral CD8 T cell responses against the TMEV immunodominant epitope VP2121-130, with functional implications both for T cell-mediated viral control and immunopathology.

T Cell Responses Directed Against HLA A*0201-Restricted Epitopes Derived from WT1 Are Readily Identifiable in Patients with AML and CML, but Not in Patients with ALL.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2526-2526
Author(s):  
Katayoun Rezvani ◽  
Jason Brenchley ◽  
David Price ◽  
Yasemin Kilical ◽  
Matthias Grube ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Mhc Class I ◽  
Cd8 T Cells ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Cell Responses ◽  
Healthy Donors ◽  
Myeloid Leukemias

Abstract The WT1 gene contributes to leukemogenesis and all adult ALL, AML and CML express WT1 RNA by quantitative real-time reverse transcription polymerase chain reaction (qPCR) techniques. WT1 may therefore be a useful antigenic target for immunotherapy. Four HLA-A*0201-restricted WT1 T cell epitopes have been identified: Db126 (RMFPNAPYL), WH187 (SLGEQQYSV), WT37-45 (VLDFAPPGA) and WT235 (CMTWNQMNL), but only Db126 has been extensively studied in myeloid leukemias. Here, we sought CD8+ T cells directed against these epitopes in 12 healthy SCT donors, 6 patients with AML, 8 with, CML and 6 with ALL prior to SCT. All patients tested with myeloid or lymphoid leukemias expressed MHC class I, B7.1 and WT1. To detect very low frequencies of WT1-specific CD8+ T cells, we used qPCR for interferon-g (IFN-g) mRNA. After isolation, 106 CD8+ T cells were stimulated with C1R-A2 cells (MHC class I-defective LCL cells transfected with HLA-A*0201) loaded with test peptides at concentrations of 0.1, 1 and 10 mM to determine their functional avidity. CD8+ T cells were also stimulated with CMV pp65 (positive control) and gp100 (209-2M) (negative control) peptides. After 3 hr coculture, cells were harvested for RNA extraction and cDNA synthesis. qPCR was performed for IFN-g mRNA and normalized to copies of CD8 mRNA from the same sample. Parallel assays using tetramers demonstrated that the IFN-g copy number was linearly related to the frequency of tetramer-binding T cells, sensitive to frequencies of 1 responding CD8+ T cell/100 000 CD8+ T cells. A positive response was defined as a threshold of 100 or more IFN-g mRNA copies/104 CD8 copies and a stimulation index (SI) of 2 or more, where SI = IFN-g mRNA copies/104 CD8 copies in peptide pulsed/unpulsed cultures. Responses to at least one WT1 peptide were detected in 5/8 CML patients, 4/6 patients with AML and 7/12 healthy donors. Notably, a response was not elicited to WT1 in any of the 6 patients with ALL, despite evidence of immune competence as shown by a normal CMV response. Five of five CML responders and 3/4 AML responders recognized 2 or more WT1 epitopes, while the 7 healthy donors recognized only one WT1 epitope. The range of IFN-g mRNA copies/104 CD8 copies was 289–13584, 418–45891 and 160–2683 for CML, AML and healthy donors respectively. WT1-specific tetramer-positive CD8+ T cells displayed both central memory (CD45RO+CD27+CD57−) and terminally differentiated effector memory phenotypes (CD45RO-CD27−CD57+). As multiple WT1-derived epitopes can be targeted simultaneously, it is likely that T cell response to WT1 is polyclonal. These results are important because the presence of memory WT1 responses in patients with myeloid leukemias and healthy individuals should favor vaccination as a means to expand immune responses to leukemia in the autologous and allogeneic transplant setting. Furthermore, the presence of CD8+ T cell responses to multiple WT1 epitopes should favor robust polyclonal immune responses to leukemia. However, failure to detect CD8+ T cell responses to WT1 in ALL patients suggests that WT1 may not be a useful antigen to target for immunotherapeutic purposes in this patient group.

Identification of Novel MHC Class I and Class II Epitopes of WT1 Using a Peptide Library Screen.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2764-2764 ◽  
Author(s):  
Katayoun Rezvani ◽  
Stephan Mielke ◽  
Yasemin Kilical ◽  
Matthias Grube ◽  
Hiroshi Fujiwara ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mhc Class I ◽  
Cd8 T Cells ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Class Ii ◽  
Peptide Library ◽  
Class I ◽  
Cell Responses

Abstract Although several HLA-A*0201-restricted immunodominant peptides from the leukemia-restricted protein WT-1 are characterized, T cell responses to peptide sequences binding to other common class I and II epitopes of WT-1 remain almost completely unexplored. A more comprehensive definition of the WT-1 antigen would extend peptide antigen vaccines to individuals lacking HLA-A*0201 and *2402 and improve vaccine potency by recruiting both CD4+ and CD8+ T cell responses. Here we used a WT1 peptide library to identify WT-1 peptide sequences inducing CD4+ and CD8+ T cell responses in normal individuals and patients with AML and other myeloid leukemias. Six cases were studied. The library consisted of 110 15mer peptides overlapping by 11aa covering the entire WT-1 protein in 21 pools. Monocytes were isolated by plastic adherence and pulsed with peptide pools for 3 hours. Autologous CD8+ and CD4+ T cells were then added. Pools of peptides were prepared in such a way that each peptide was represented in two different peptide pools, allowing the identification of the respective peptide by responses in the two corresponding pools. Cells were harvested for RNA extraction and reverse transcription. Real time PCR (RQ-PCR) was used to identify peptide-specific induction of IFN-γ and IL-2 in CD8+ and CD4+ T cells. The SYFPEITHI binding motif software was then used to predict the probable HLA restriction for the candidate epitopes. To confirm candidate peptide immunogenecity and HLA restriction, selected peptides were synthesized and tested individually. In addition to the known HLA-A*0201 peptides WT37, WT126, WT187 and WT235 we identified 20 new MHC class I and II epitopes of WT1. Four were restricted by more than one HLA allele, demonstrating the promiscuity of epitope binding. One epitope (VPGVAPTLV) was restricted to HLA-A*0201 and HLA-B*5101. One epitope (SGQFTGTAGACRYGP) was restricted by a class I HLA allele, namely HLA-*6801 and a class II HLA allele, DR*1501. Two epitopes (YGPFGPPPPSQASGQ and QKKFARSDELVRHHN) were restricted by multiple MHC class II alleles. The proliferative response of CD4+ and CD8+ T cells to candidate peptides was confirmed using CFSE labeling. We now plan to characterize the antileukemic effects of CD4+ and CD8+ T cells induced by these peptides with a view to designing broad-spectrum vaccines inducing leukemia-reactive T cells across a wide range of HLA types.

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