Prevention Of Murine FVIII-Specific Memory B Cells Due To FcγR2B (CD32) Blockade Is Associated With Distinctive Alterations In The FVIII-Specific Cytokine Profile

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 572-572
Author(s):  
Nadine Vollack ◽  
Arne Trummer ◽  
Andreas Tiede ◽  
Sonja Werwitzke
Keyword(s):  
T Cell ◽  
B Cells ◽  
Cell Response ◽  
Research Funding ◽  
Hemophilia A ◽  
T Cell Response ◽  
Memory B Cells ◽  
Ifn Γ ◽  
High Doses ◽  
Very High

Abstract Development of neutralizing antibodies against factor VIII (FVIII) is a severe complication of replacement therapy in hemophilia A. Long-term application of high doses of FVIII can induce tolerance in the context of immune tolerance therapy (ITT). Very high concentrations of FVIII have been shown to prevent the development of FVIII-specific antibody-secreting cells (ASCs) from memory B cells by inducing apoptosis. We have previously demonstrated that ASC differentiation from memory B cells is also abolished when CD32, an inhibitory Fc-gamma receptor expressed on B cells and dendritic cells, was genetically deleted or blocked by monoclonal antibodies (mAb). Here, we addressed the question how CD32 inhibition prevented ASC development by studying the FVIII-specific T cell response in the absence or presence of CD32 inhibition. Hemophilia A mice (B6;129S4-F8tmKaz/J) were immunized with recombinant human FVIII (rhFVIII) for 4 weeks, and spleen cells were re-stimulated with rhFVIII (0, 0.5, 1 or 10 IU/ml) ex vivo in the presence or absence of anti-CD16/CD32 antibody (2.4G2) to inhibit CD32. Formation of FVIII-specific ASCs was assessed on day 6 by ELISPOT. IFN-γ, IL-2, IL-4, IL-6, IL-10, and TNF-α were detected in culture supernatant using a cytometric bead-based multiplex assay on days 1 to 6. In line with previous findings, very high doses of rhFVIII (10 IU/ml) or blockade of CD32 with mAb 2.4G2 (at high or low doses of rhFVIII) inhibited the differentiation of FVIII-specific ASCs. We observed a FVIII-dose dependent increase in the secretion of IFN-γ, IL-2, IL-4, IL-6, and IL-10. Very high doses of rhFVIII (10 IU/ml) suppressed ACS formation, but not the formation of these cytokines indicating an intact FVIII-specific T cell response. Secretion of TNF-α appeared not to be FVIII-dose dependent and was also observed in the cultures without rhFVIII. Inhibition of CD32 with mAb 2.4G2 in the presence of ASC stimulating FVIII concentrations (e.g. 1 IU/ml) prevented the development of ASC, but also diminished the formation of IFN-γ (334.2 ± 58.0 pg/ml versus 14.9 ± 1.4 pg/ml) and significantly reduced IL-10 (297.7 ± 78.5 pg/ml versus 131.3 ± 26.8 pg/ml). IL-6 was only slightly reduced, whereas IL-4 remained unchanged. IL-2 was even increased at later time points during cell culture (day 4: 16.1 ± 3.4 pg/ml versus 24.0 ± 1.4 pg/ml, day 6: 3.1 ± 0.6 pg/ml versus 21.8 ± 3.6 pg/ml). These results indicate that very high doses of FVIII prevented ASC formation, but not FVIII-specific T cell stimulation. In contrast, inhibition of CD32 prevented ASC formation, but also changed the secretion of T cell dependent cytokines. The lack of IFN-γ and IL-10 production after re-stimulation with various doses of rhFVIII indicates a reduced stimulation of Th1 and Th2 helper cells. Similar effects have been described previously, when B7-1 co-stimulation of CD4+ T cells was prevented by anti-CD80 mAb. In conclusion, inhibition of FVIII-specific ASC formation by means of very high doses of FVIII or inhibition of CD32 appears to occur differently. High doses of FVIII induce apoptosis in FVIII-specific memory B cells, but do not prevent FVIII-specific T cell responses. In contrast, inhibition of the Fcγ receptor CD32 on B cells and dendritic cells interferes with the FVIII-specific T cell response indicating a defective antigen presentation. Both high dose FVIII treatment and CD32 blockade, alone or in combination, should be further investigated to specifically address the FVIII-specific immune response in hemophilia A, and to evaluate a potential improvement of ITT. Disclosures: Vollack: Biotest AG: Research Funding. Trummer:Biotest AG: Research Funding. Tiede:CSL Behring: Consultancy, Honoraria, Research Funding; Biogen Idec: Consultancy; Novo Nordisk: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Biotest: Consultancy, Honoraria, Research Funding; Bayer: Consultancy, Honoraria, Research Funding; Baxter: Consultancy, Honoraria, Research Funding. Werwitzke:Biotest AG: Honoraria, Research Funding.

Cultured Human B Cell APCs Expanded Using Il-4 and CD40 Ligand Preferentially Promote a Type 2 T Cell Response to Alloimmune Stimulation.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2668-2668
Author(s):  
Abdul Tawab ◽  
Yoshiyuki Takahashi ◽  
Childs Richard ◽  
Kurlander J. Roger
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
Cell Response ◽  
Cd40 Ligand ◽  
T Cell Response ◽  
Ifn Γ

Abstract In vitro stimulation of human peripheral blood B cells with recombinant IL-4 and CD40 ligand (CD40L) markedly increases their expression of MHC and costimulatory molecules, thus enhancing antigenic peptide presentation to T cells. Because these cells proliferate extensively in vitro (unlike monocytes or dendritic cells), they represent a promising and convenient reagent for the generation and maintenance of antigen-specific T cells for use in a variety of experimental or therapeutic settings. However, the impact of this type of B cell APC on cytokine production by responder T cells has hitherto not been examined. To address this issue, we stimulated normal human T cells with either allogeneic B cells (generated in vitro) or with MNCs obtained from the same donor. After 7 days, T cells were washed and re-challenged with the same APCs. The resulting alloreactive cytokine response was measured using quantitative ELISPOT methods and expressed as the frequencies of IFN-γ, IL-4, and IL-5 producing cells per thousand responder cells added. B cell- and MNC-primed cell lines both produced vigorous lymphokine responses, but B cell-stimulated T cells consistently produced more IL-5 spots (mean of 265 vs. 98/1000 responders, p<0.002) and fewer IFN-γ spots (163 vs 386/1000 cells, p<0.005) than MNC-stimulated cells. Further, the ratio of IFN-γ to IL-5 spots was almost ten-fold lower in B cell-stimulated cultures compared to MNC-induced cultures (0.67 vs. 5.2, p<0.001). ELISPOT studies assessing the ratio of IFN-γ to IL-4 spots and ELISA assays comparing IFN-γ and IL-5 levels from culture supernatants demonstrated the same pattern of marked type 2 skewing by B cells. This pattern was unaffected by the presence of anti-IL-4 antibody suggesting type 2 skewing was not mediated by IL-4. Cytokine skewing produced by B cells or MNC could be partially reversed by swapping MNC and B cells during re-stimulation on day 7, but this plasticity was markedly reduced after 3 (weekly) cycles of B cell or MNC re-stimulation in vitro. Type 2 skewing by B cells was enhanced when monocytes were removed from responder T cell populations by either depleting CD14+ positive cells or by positive selection of T cells prior to stimulation. In contrast, type 2 polarization could be prevented using recombinant IL-12. Not all cells of B-cell origin share the same propensity to type 2 skewing observed with IL-4/CD40L-stimulated B cells; under identical conditions, EBV-transformed B cells stimulated alloimmune T cells to produce a strong type 1 cytokine response comparable to that produced by MNCs. In summary, IL-4/CD40L-stimulated B cells strongly promote a type 2 T cell response during primary alloimmune challenge; this skewing can become fixed after repeated B cell stimulation. Investigators using these cells as APC should be aware of this potential phenomenon, particularly during primary T cell responses. It is also important to consider the factors described above that may exacerbate or ameliorate this effect.

scholarly journals T-Cell Response to Human Papillomavirus Type 58 L1, E6, and E7 Peptides in Women with Cleared Infection, Cervical Intraepithelial Neoplasia, or Invasive Cancer

2010 ◽  
Vol 17 (9) ◽  
pp. 1315-1321 ◽  
Author(s):  
Paul K. S. Chan ◽  
Shih-Jen Liu ◽  
T. H. Cheung ◽  
Winnie Yeo ◽  
S. M. Ngai ◽  
...  
Keyword(s):  
Human Papillomavirus ◽  
Amino Acid ◽  
T Cell ◽  
Cell Response ◽  
Positive Response ◽  
Intraepithelial Neoplasia ◽  
Amino Acid Position ◽  
T Cell Response ◽  
Ifn Γ ◽  
E6 And E7

ABSTRACT Human papillomavirus type 58 (HPV-58) exists in a relatively high prevalence in certain parts of the world, including East Asia. This study examined the T-cell response to HPV-58 L1, E6, and E7 peptides among women with cleared infection, cervical intraepithelial neoplasia grade 2 (CIN2) or CIN3, or invasive cervical cancer (ICC). Peptides found to be reactive in the in vitro peptide binding assay or mouse-stimulating study were tested with a gamma interferon (IFN-γ) enzyme-linked immunospot (ELISPOT) assay to detect peptide-specific responses from the peripheral blood mononuclear cells (PBMC) collected from 91 HPV-58-infected women (32 with cleared infection, 16 CIN2, 15 CIN3, and 28 ICC). Four HLA-A11-restricted HPV-58 L1 peptides, located at amino acid positions 296 to 304, 327 to 335, 101 to 109, and 469 to 477, showed positive IFN-γ ELISPOT results and were mainly from women with cleared infection. Two HLA-A11-restricted E6 peptides (amino acid positions 64 to 72 and 94 to 102) and three HLA-A11-restricted E7 peptides (amino acid positions 78 to 86, 74 to 82, and 88 to 96) showed a positive response. A response to E6 and E7 peptides was mainly observed from subjects with CIN2 or above. One HLA-A2-restricted E6 peptide, located at amino acid position 99 to 107, elicited a positive response in two CIN2 subjects. One HLA-A24-restricted L1 peptide, located at amino acid position 468 to 476, also elicited a positive response in two CIN2 subjects. In summary, this study has identified a few immunogenic epitopes for HPV-58 E6 and E7 proteins. It is worthwhile to further investigate whether responses to these epitopes have a role in clearing an established cervical lesion.

scholarly journals An Adaptive Chlamydia trachomatis-Specific IFN-γ-Producing CD4+ T Cell Response Is Associated With Protection Against Chlamydia Reinfection in Women

2018 ◽  
Vol 9 ◽  
Author(s):  
Rakesh K. Bakshi ◽  
Kanupriya Gupta ◽  
Stephen J. Jordan ◽  
Xiaofei Chi ◽  
Shelly Y. Lensing ◽  
...  
Keyword(s):  
T Cell ◽  
Chlamydia Trachomatis ◽  
Cell Response ◽  
T Cell Response ◽  
Cd4 T Cell ◽  
Ifn Γ

scholarly journals The Polyomavirus BK Large T-Antigen-Derived Peptide Elicits an HLA-DR Promiscuous and Polyfunctional CD4+T-Cell Response

2011 ◽  
Vol 18 (5) ◽  
pp. 815-824 ◽  
Author(s):  
Bala Ramaswami ◽  
Iulia Popescu ◽  
Camila Macedo ◽  
Chunqing Luo ◽  
Ron Shapiro ◽  
...  
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Cell ◽  
Cell Response ◽  
T Antigen ◽  
T Cell Response ◽  
Peptide Sequence ◽  
Large T Antigen ◽  
Hla Dr ◽  
Ifn Γ

ABSTRACTBK virus (BKV) nephropathy and hemorrhagic cystitis are increasingly recognized causes of disease in renal and hematopoietic stem cell transplant recipients, respectively. Functional characterization of the immune response to BKV is important for clinical diagnosis, prognosis, and vaccine design. A peptide mix (PepMix) and overlapping (OPP) or random (RPP) peptide pools derived from BKV large T antigen (LTA) were used to restimulate 14-day-expanded peripheral blood mononuclear cells (PBMC) from 27 healthy control subjects in gamma interferon (IFN-γ)-specific enzyme-linked immunospot (ELISPOT) assays. A T-cell response to LTA PepMix was detected in 15/27 subjects. A response was frequently observed with peptides derived from the helicase domain (9/15 subjects), while the DNA binding and host range domains were immunologically inert (0/15 subjects). For all nine subjects who responded to LTA peptide pools, the immune response could be explained largely by a 15-mer peptide designated P313. P313-specific CD4+T-cell clones demonstrated (i) stringent LTA peptide specificity; (ii) promiscuous recognition in the context of HLA-DR alleles; (iii) cross recognition of homologous peptides from the polyomavirus simian virus 40 (SV40); (iv) an effector memory phenotype, CD107a expression, and intracellular production of IFN-γ and tumor necrosis factor alpha (TNF-α); (v) cytotoxic activity in a chromium release assay; and (vi) the ability to directly present cognate antigen to autologous T cells. In conclusion, T-cell-mediated immunity to BKV in healthy subjects is associated with a polyfunctional population of CD4+T cells with dual T-helper and T-cytotoxic properties. HLA class II promiscuity in antigen presentation makes the targeted LTA peptide sequence a suitable candidate for inclusion in immunotherapy protocols.

The Role of B Cells in the Establishment of T Cell Response in Mice Infected with an Intracellular Bacteria, Listeria monocytogenes

1999 ◽  
Vol 194 (2) ◽  
pp. 178-185 ◽  
Author(s):  
Goro Matsuzaki ◽  
H.Martin Vordermeier ◽  
Asako Hashimoto ◽  
Kikuo Nomoto ◽  
Juraj Ivanyi
Keyword(s):  
Listeria Monocytogenes ◽  
T Cell ◽  
B Cells ◽  
Cell Response ◽  
T Cell Response ◽  
Intracellular Bacteria

Rapid establishment of a stable IL-4/IFN-γ production profile in the antigen-specific CD4+ T cell response to protein immunization

1994 ◽  
Vol 6 (10) ◽  
pp. 1515-1523 ◽  
Author(s):  
Anne Kelso ◽  
Penny Groves ◽  
Anthony B. Troutt ◽  
Michael H. Pech
Keyword(s):  
T Cell ◽  
Cell Response ◽  
T Cell Response ◽  
Cd4 T Cell ◽  
Ifn Γ ◽  
Protein Immunization

scholarly journals The CD8+ T-Cell Response to Lymphocytic Choriomeningitis Virus Involves the L Antigen: Uncovering New Tricks for an Old Virus

2007 ◽  
Vol 81 (10) ◽  
pp. 4928-4940 ◽  
Author(s):  
Maya F. Kotturi ◽  
Bjoern Peters ◽  
Fernando Buendia-Laysa ◽  
John Sidney ◽  
Carla Oseroff ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Response ◽  
Cellular Response ◽  
Lymphocytic Choriomeningitis ◽  
Lymphocytic Choriomeningitis Virus ◽  
T Cell Response ◽  
Ifn Γ ◽  
Lcmv Infection

ABSTRACT CD8+ T-cell responses control lymphocytic choriomeningitis virus (LCMV) infection in H-2b mice. Although antigen-specific responses against LCMV infection are well studied, we found that a significant fraction of the CD8+ CD44hi T-cell response to LCMV in H-2b mice was not accounted for by known epitopes. We screened peptides predicted to bind major histocompatibility complex class I and overlapping 15-mer peptides spanning the complete LCMV proteome for gamma interferon (IFN-γ) induction from CD8+ T cells derived from LCMV-infected H-2b mice. We identified 19 novel epitopes. Together with the 9 previously known, these epitopes account for the total CD8+ CD44hi response. Thus, bystander T-cell activation does not contribute appreciably to the CD8+ CD44hi pool. Strikingly, 15 of the 19 new epitopes were derived from the viral L polymerase, which, until now, was not recognized as a target of the cellular response induced by LCMV infection. The L epitopes induced significant levels of in vivo cytotoxicity and conferred protection against LCMV challenge. Interestingly, protection from viral challenge was best correlated with the cytolytic potential of CD8+ T cells, whereas IFN-γ production and peptide avidity appear to play a lesser role. Taken together, these findings illustrate that the LCMV-specific CD8+ T-cell response is more complex than previously appreciated.

The Response to Repeated Vaccination with PR1 and WT1 Peptides Admixed in Montanide Adjuvant Is Transient and Fails to Induce Sustained Anti-Leukemia Responses in Patients with Myeloid Malignancies.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 4096-4096
Author(s):  
Katayoun Rezvani ◽  
Agnes S. M. Yong ◽  
Stephan Mielke ◽  
Behnam Jafarpour ◽  
Bipin N. Savani ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Cell Response ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
T Cell Response ◽  
Gm Csf ◽  
Cell Responses ◽  
Ifn Γ

Abstract Abstract 4096 Poster Board III-1031 We previously demonstrated the immunogenicity of a combined vaccine approach employing two leukemia-associated antigenic peptides, PR1 and WT1 (Rezvani Blood 2008). Eight patients with myeloid malignancies received one subcutaneous 0.3 mg and 0.5 mg dose each of PR1 and WT1 vaccines in Montanide adjuvant, with 100 μg of granulocyte-macrophage colony-stimulating factor (GM-CSF). CD8+ T-cell responses against PR1 or WT1 were detected in all patients as early as 1 week post-vaccination. However, responses were only sustained for 3-4 weeks. The emergence of PR1 or WT1-specific CD8+ T-cells was associated with a significant but transient reduction in minimal residual disease (MRD) as assessed by WT1 expression, suggesting a vaccine-induced anti-leukemia response. Conversely, loss of response was associated with reappearance of WT1 transcripts. We hypothesized that maintenance of sustained or at least repetitive responses may require frequent boost injections. We therefore initiated a phase 2 study of repeated vaccination with PR1 and WT1 peptides in patients with myeloid malignancies. Five patients with acute myeloid leukemia (AML) and 2 patients with myelodysplastic syndrome (MDS) were recruited to receive 6 injections at 2 week intervals of PR1 and WT1 in Montanide adjuvant, with GM-CSF as previously described. Six of 7 patients completed 6 courses of vaccination and follow-up as per protocol, to monitor toxicity and immunological responses. Responses to PR1 or WT1 vaccine were detected in all patients after only 1 dose of vaccine. However, additional boosting did not further increase the frequency of PR1 or WT1-specific CD8+ T-cell response. In 4/6 patients the vaccine-induced T-cell response was lost after the fourth dose and in all patients after the sixth dose of vaccine. To determine the functional avidity of the vaccine-induced CD8+ T-cell response, the response of CD8+ T-cells to stimulation with 2 concentrations of PR1 and WT1 peptides (0.1 and 10 μM) was measured by IC-IFN-γ staining. Vaccination led to preferential expansion of low avidity PR1 and WT1 specific CD8+ T-cell responses. Three patients (patients 4, 6 and 7) returned 3 months following the 6th dose of PR1 and WT1 peptide injections to receive a booster vaccine. Prior to vaccination we could not detect the presence of PR1 and WT1 specific CD8+ T-cells by direct ex-vivo tetramer and IC-IFN-γ assay or with 1-week cultured IFN-γ ELISPOT assay, suggesting that vaccination with PR1 and WT1 peptides in Montanide adjuvant does not induce memory CD8+ T-cell responses. This observation is in keeping with recent work in a murine model where the injection of minimal MHC class I binding peptides derived from self-antigens mixed with IFA adjuvant resulted in a transient effector CD8+ T cell response with subsequent deletion of these T cells and failure to induce CD8+ T cell memory (Bijker J Immunol 2007). This observation can be partly explained by the slow release of vaccine peptides from the IFA depot without systemic danger signals, leading to presentation of antigen in non-inflammatory lymph nodes by non-professional antigen presenting cells (APCs). An alternative explanation for the transient vaccine-induced immune response may be the lack of CD4+ T cell help. In summary these data support the immunogenicity of PR1 and WT1 peptide vaccines. However new approaches will be needed to induce long-term memory responses against leukemia antigens. To avoid tolerance induction we plan to eliminate Montanide adjuvant and use GM-CSF alone. Supported by observations that the in vivo survival of CD8+ T-effector cells against viral antigens are improved by CD4+ helper cells, we are currently attempting to induce long-lasting CD8+ T-cell responses to antigen by inducing CD8+ and CD4+ T-cell responses against class I and II epitopes of WT1 and PR1. Disclosures: No relevant conflicts of interest to declare.

Modification of Predicted Inhibitor Risk in Non-Severe Hemophilia-a By in silico Analysis of Human Proteome Homology with Wild-Type, FVIII-Derived Peptides

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 290-290
Author(s):  
Adrian Shepherd ◽  
Stuart Skelton ◽  
David Moss ◽  
Dan Hart
Keyword(s):  
T Cell ◽  
Cell Response ◽  
In Silico ◽  
Hemophilia A ◽  
T Cell Response ◽  
Human Proteome ◽  
Wild Type ◽  
Mhc Ii ◽  
Class Ii Mhc ◽  
Factor Concentrate

Abstract Neutralising antibodies (inhibitors) are increasingly recognized to be a life-time risk in non-severe hemophilia A patients exposed to factor VIII concentrates. It is currently not possible to reliably identify the variable inhibitor risk between individuals. Risk appears to differ between F8 genotypes but also for individuals living with the same F8 genotype. As a T cell dependent process, the wild-type, factor concentrate-derived peptide sequences spanning the F8 mutation position are presented by class II MHC and responsible for driving the T helper response and subsequent B cell response. We hypothesize that the primary sequences of the 20,469 proteins in the human proteome will, coincidentally, contain short primary sequences homologous to key immunogenic peptides derived from the therapeutic factor VIII. We present in silico data and correlation with published registry inhibitor data (Fisher's exact test) to demonstrate the potential impact of such "proteome protection" and future potential to more reliably stratify individuals between low/negligible risk and more significant risk of inhibitor formation. We utilize a well-validated, computational tool, NetMHC-II, to enable large scale, computational comparison of predicted antigen presentation between endogenous, mutated FVIII derived peptides and factor-concentrate derived, wild-type FVIII peptides spanning all 520 F8 missense mutations listed on www.hadb.org. NetMHC-II analyses peptide presentation by 14 class II MHC HLA-DR alleles, resulting in analysis of 7,280 (520 x 14) permutations of F8 -MHC-II. We identify 56% (n=4,077) of these permutations to be at low/negligible risk of inhibitor formation, at a binding threshold of 500nM, defined as absence of a novel peptide-MHC surface capable of driving a helper T cell response (p=0.005). When cross referenced with potential homologous sequences buried anywhere in the human proteome (http://www.ebi.ac.uk/reference_proteomes), a further 1,237 F8 -MHC-II combinations are afforded "proteome protection" due to direct sequence homology between FVIII-derived peptide and peptide(s) derived from other proteins. This increases the total number of F8 -MHC-II combinations predicted to be unable to drive a T cell response to 73% (n=5,314). The residual 1,966 (27%) F8 -MHC-II combinations are predicted to retain the ability to present novel-interface FVIII-derived peptides to T cells with an IC50<500nM (higher affinity). Previous work exploring in silico prediction of FVIII-derived peptide presentation may have overestimated the number of F8 -MHC II combinations deemed to be at risk of contributing to inhibitor formation. Our data suggests an additional mechanism "protecting" a larger proportion of those living with non-severe HA from inhibitor formation. The contribution of "proteome protection" further reduces the "at risk" F8 -MHC II permutations to be more representative of clinically observed inhibitor rates. We identify a potential novel tolerance mechanism and provide key data for future in vitro validation strategies. Disclosures No relevant conflicts of interest to declare.

scholarly journals Safety and Immunogenicity of DNA Prime and Modified Vaccinia Ankara Virus-HIV Subtype C Vaccine Boost in Healthy Adults

2013 ◽  
Vol 20 (3) ◽  
pp. 397-408 ◽  
Author(s):  
Peter Hayes ◽  
Jill Gilmour ◽  
Andrea von Lieven ◽  
Dilbinder Gill ◽  
Lorna Clark ◽  
...  
Keyword(s):  
T Cell ◽  
Vaccinia Virus ◽  
Cell Response ◽  
T Cell Response ◽  
Antibody Responses ◽  
Cell Responses ◽  
Group A ◽  
Ifn Γ ◽  
Group B

ABSTRACTA randomized, double-blind, placebo-controlled phase I trial was conducted in 32 HIV-uninfected healthy volunteers to assess the safety and immunogenicity of 3 doses of DNA vaccine (Advax) plus 1 dose of recombinant modified vaccinia virus Ankara (MVA) (TBC-M4) or 3 doses of TBC-M4 alone (groups A and B, respectively). Both vaccine regimens were found to be safe and well tolerated. Gamma interferon (IFN-γ) enzyme-linked immunosorbent spot (ELISPOT) assay responses were detected in 1/10 (10%) individuals in group A after three Advax primes and in 9/9 individuals (100%) after the MVA boost. In group B, IFN-γ ELISPOT responses were detected in 6/12 (50%) and 7/11 (64%) individuals after the second and third MVA vaccinations, respectively. Responses to all vaccine components, but predominantly to Env, were seen. The breadth and magnitude of the T cell response and viral inhibition were greater in group A than in group B, indicating that the quality of the T-cell response was enhanced by the DNA prime. Intracellular cytokine staining indicated that the T-cell responses were polyfunctional but were skewed toward Env with a CD4+phenotype. At 2 weeks after the last vaccination, HIV-specific antibody responses were detected in all (100%) group B and 1/11 (9.1%) group A vaccinees. Vaccinia virus-specific responses were detected in all (100%) group B and 2/11 (18.2%) group A vaccinees. In conclusion, HIV-specific T-cell responses were seen in the majority of volunteers in groups A and B but with a trend toward greater quality of the T-cell response in group A. Antibody responses were better in group B than in group A.

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