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Mark Peakman

Publications and source records attributed to Mark Peakman.

At least 19 recordsLinked to original sources
PubMed2006

Long-lasting T cell responses to biological warfare vaccines in human vaccinees.

BACKGROUND: Medical countermeasures against biological warfare include the use of vaccines for anthrax and plague, which require repeated dosing and adjuvant to achieve adequate protection from threats such as inhalational anthrax and pneumonic plague. Despite the widespread use of these measures in preparation for recent military deployments, little is known about the cell-mediated immune response that is induced by these vaccines, in comparison with conventional vaccines, such as pertussis or tetanus-diphtheria vaccines. METHODS: To examine this question, we used cytokine enzyme-linked immunospot assays to measure interferon-gamma, interleukin (IL)-2, IL-4, and IL-13-producing cells in military service personnel vaccinated during the Gulf War of 1990-1991. RESULTS: Our data indicate that 12-15 years after vaccination against anthrax and plague, antigen-specific T cell recall responses are present in the circulation and are comparable in magnitude to those for tetanus-diphtheria toxoids. Recall responses to anthrax were an approximately equal mixture of type 1 T helper cell (interferon-gamma and IL-2) and type 2 T helper cell (predominantly IL-13) responses, whereas plague cellular immunity was more polarized toward type 1 T helper cell responses. Responder cell frequency and type were similar to that against conventional tetanus-diphtheria (mixed type 1 and type 2 T helper cells) vaccine. When veterans were divided according to whether or not they reported multisymptom illness, there was no difference in the frequency or type of cellular response, although the number of cases in each group was small, and these data should be interpreted as preliminary. CONCLUSIONS: This study shows that, despite any putative limitations of vaccines for anthrax and plague in terms of achieving protective host immunity, long-lasting cell-mediated responses are generated with these agents.

Anthrax↗
PubMed2006

Immunological dysfunction, vaccination and Gulf War illness.

One candidate cause of Gulf War illness is vaccination against infectious diseases including medical counter-measures against biological weapons. One influential theory has suggested that such mass-vaccination caused a shift in immune response to a Type 2 cytokine pattern (Th2), which it was suggested was accompanied by a chronic fatigue syndrome-like illness. This article critically appraises this theory. We start by examining epidemiological evidence, which indicates that single vaccines are unlikely to be a substantial cause of Gulf War illness, but that there was a modest relationship with multiple vaccines, which was strongest in those vaccinated while deployed to the Gulf. These relationships may be affected by recall bias. We conclude by examining the results of immunological studies carried out in veterans or in a relevant setting in vitro. The balance of evidence from immunological studies on veterans returning from the War, including those developing multi-symptom illness, is that the immune response has not become polarized towards Th2. In summary, the epidemiological evidence for a multiple vaccine effect on Gulf War-related illness remains a potentially important aetiological lead, but mechanistic studies available at this stage do not identify any immunological basis for it.

Cytokines↗
PubMed2006

A mini meta-analysis of studies on CD4+CD25+ T cells in human type 1 diabetes: report of the Immunology of Diabetes Society T Cell Workshop.

Type 1 diabetes mellitus (T1DM) is characterized by a loss of self-tolerance to islet antigens. In health, immunological tolerance is maintained by multiple central and peripheral mechanisms including the action of a specialized set of regulatory T cells characterized by expression of CD4 and CD25 (CD4+CD25+ Treg). It has been suggested that a defect in this cell population, either numerically or functionally, could contribute to the development of autoimmune diseases, such as T1DM. To investigate this possibility, several research groups have studied the frequency and suppressive capacity of this cell population in individuals with T1DM and, to date, there are four such studies published. We therefore performed a mini meta-analysis to compare the results in the four published studies, account for differences in their findings, and draw a consensus view on the role of this important cell subset in human T1DM.

Antigens, CD↗
PubMed2006

HLA class I epitope discovery in type 1 diabetes: independent and reproducible identification of proinsulin epitopes of CD8 T cells--report of the IDS T Cell Workshop Committee.

Islet autoreactive CD8 T cells are plausible candidates for direct beta cell toxicity in type 1 diabetes (T1DM). In 2005, cellular studies in the pathogenesis of this disease have reached a new milestone. Autoreactive CD8 T cells have been defined and several target islet epitopes of these have been discovered and validated simultaneously in three independent studies. The insulin B10-B18 peptide that displays exceptional binding affinity for HLA-A2 has been reported in all three studies, and its recognition shows an association with autoimmune beta cell destruction and T1DM. These studies imply that CD8 T cell-based HLA tetramers and ELISPOT analyses can be useful to monitor T1DM as well as islet transplantation, and may provide useful tools to assess immunological efficacy of immune intervention trials.

Animals↗
PubMed2006

Atorvastatin fails to prevent the development of autoimmune diabetes despite inhibition of pathogenic beta-cell-specific CD8 T-cells.

Statins, the widely used inhibitors of cholesterol biosynthesis, also have immunomodulatory properties. Statins have recently been shown to have beneficial prophylactic and therapeutic effects in actively induced, short-term animal models of the autoimmune diseases multiple sclerosis and rheumatoid arthritis, leading to clinical trials. We therefore investigated whether statins' protective effects could be reproduced in the nonobese diabetic (NOD) mouse, a spontaneous, chronic model of autoimmune diabetes. Mice were treated with 0, 1, 10, or 50 mg x kg(-1) x day(-1) oral atorvastatin from 6 or 12 weeks of age, without effect on the rate or prevalence of diabetes development, islet infiltration, or islet major histocompatibility complex class II expression. However, there was clear evidence of a disease-relevant immunological effect of statins in vivo, since short-term (12-day) treatment significantly reduced the number of proinflammatory (gamma-interferon-producing) CD8 cells recognizing a dominant pathogenic epitope. This effect was absent in mice treated for longer periods, suggesting that atorvastatin loses efficiency in inhibiting autoantigen-specific T-cells over time. This observation may explain the discrepancy between the reported success of statins in acutely induced models and the lack of it in a chronic, spontaneous model of autoimmune disease and has implications for the adoption of such therapy in humans.

Animals↗
PubMed2005

Analysis of anthrax and plague biowarfare vaccine interactions with human monocyte-derived dendritic cells.

The anti-biowarfare anthrax and plague vaccines require repeated dosing to achieve adequate protection. To test the hypothesis that this limited immunogenicity results from the nature of vaccine interactions with the host innate immune system, we investigated molecular and cellular interactions between vaccines, dendritic cells (DCs), and T cells and explored the potential for adjuvants (pertussis) to boost induction of host immunity. Human monocyte-derived DCs were matured in the presence of vaccines and analyzed for their ability to induce Th1/Th2 development from naive T cells, expression of cell surface maturation/costimulation molecules, and cytokine production. The vaccines showed different behavior patterns. Although the plague vaccine is equivalent to control maturation factors in maturation and stimulation of DCs and induces strong MLR and Th outgrowth, the anthrax vaccine is a poor inducer of DC maturation, as indicated by low levels of HLA-DR, CD86, and CD83 induction and minimal proinflammatory cytokine production. Interestingly, however, anthrax vaccine-treated DCs stimulate Th1 and Th2 outgrowth and a limited MLR response. There was no sustained negative modulatory effects of the anthrax vaccine on DCs, and its limited stimulatory effects could be overridden by coculture with pertussis. These results were supported by analysis of anthrax vaccine recall responses in subjects vaccinated using pertussis as an adjuvant, who demonstrate anthrax-specific effector T cell responses. These data show that the anthrax vaccine is a suboptimal DC stimulus that may in part explain the observation that it requires repeated administration in vivo and offer a rational basis for the use of complementary DC-maturing adjuvants in combined immunotherapy.

Adjuvants, Immunologic↗
PubMed2005

HLA Class II molecules on haplotypes associated with type 1 diabetes exhibit similar patterns of binding affinities for coxsackievirus P2C peptides.

Enteroviruses such as coxsackievirus B4 (CVB4) are proposed as possible environmental triggers or accelerants of the autoimmune process that leads to type 1 diabetes mellitus. One putative mechanism to account for this association is mimicry between virus components and islet autoantigens. Particular interest has focused on the CVB4 non-structural protein P2C, which we previously showed to be a major target of the effector memory anti-CVB4 CD4 T-cell response, and which harbours a region of sequence similarity with the islet autoantigen, glutamic acid decarboxylase (GAD65). Since several distinct human leucocyte antigen (HLA) Class II molecules are associated with development of type 1 diabetes, we hypothesized that for functional mimicry to be important, any potential region(s) of mimicry in P2C should bind to each of these susceptibility molecules. In the present study therefore we examined the affinity of 20-mer overlapping P2C peptides for soluble HLA-DR4, -DR3, -DQ2 and -DQ8. We identified one discrete region of P2C with high binding affinities for all of these HLA Class II molecules. Moreover, the binding affinity of P2C peptides was significantly correlated between HLA molecules present on the same susceptibility haplotype (e.g. DR4 and DQ8, P =0.0076; DR3 and DQ2 P = 0.002). We conclude that possession of these haplotypes favours restricted presentation of viral epitopes, and speculate that this could promote the potential for mimicry between microbial proteins and islet autoantigens.

Amino Acid Sequence↗
PubMed2005

Defective suppressor function in CD4(+)CD25(+) T-cells from patients with type 1 diabetes.

Type 1 diabetes is a T-cell-mediated disease that is associated with loss of immunological tolerance to self-antigens. The mechanisms involved in maintenance of peripheral tolerance include a specialized subset of regulatory T-cells (Treg) within the CD4(+)CD25(+) T-cell population, but the function and phenotype of these cells in type 1 diabetes have not been investigated. We hypothesized that a deficiency in the CD4(+)CD25(+) Treg population or its function could contribute to the lack of self-tolerance evident in patients with type 1 diabetes. We show that although levels of CD4(+)CD25(+) T-cells are normal in patients with recent-onset adult type 1 diabetes, the ability of the Tregs in this population to suppress T-cell proliferation during in vitro cocultures is markedly reduced compared with control subjects (P = 0.007). Moreover, in patients with type 1 diabetes, these cocultures display a more proinflammatory phenotype, with increased secretion of interferon-gamma (P = 0.005) and decreased interleukin-10 production (P = 0.03). These deficiencies may reflect a disturbance in the balance of the CD4(+)CD25(+) population, because in patients with type 1 diabetes, a higher proportion of these cells coexpress the early activation marker CD69 (P = 0.007) and intracellular CTLA-4 (P = 0.01). These data demonstrate deficiency in function of the CD4(+)CD25(+) Treg population that may influence the pathogenesis of type 1 diabetes.

Adult↗
PubMed2005

Autoantibodies to autonomic nerves associated with cardiac and peripheral autonomic neuropathy.

OBJECTIVE: This study examines whether autonomic nerve autoantibodies (ANabs) are associated with development of autonomic neuropathy using a prospective study design. RESEARCH DESIGN AND METHODS: A group of type 1 diabetic patients were followed prospectively with regard to autonomic nerve function on four occasions. At the third examination, 41 patients were tested for ANabs (complement-fixing autoantibodies to the sympathetic ganglion, vagus nerve, and adrenal medulla), and the results were related to cardiac autonomic nerve function (heart rate variation during deep breathing [expiration/inspiration ratio] and heart-rate reaction to tilt [acceleration and brake index]) and to peripheral sympathetic nerve function (vasoconstriction after indirect cooling [vasoconstriction index]). RESULTS: ANabs were detected in 23 of 41 (56%) patients at the third examination. Compared with patients without ANabs (ANabs-), patients with ANabs (ANabs+) showed significantly higher frequencies of at least one abnormal cardiac autonomic nerve function test at the third examination (17 of 23 [74%] vs. 7 of 18 [39%]; P = 0.03) and fourth examination (15 of 21 [71%] vs. 4 of 16 [25%]; P < 0.01). In contrast, there was no similar difference at the first or second examination. The relative risk for ANabs(+) patients to develop cardiac autonomic neuropathy at follow-up was 7.5 (95% CI 1.72-32.80). The vasoconstriction index was more abnormal in ANabs+ than in ANabs- patients at the fourth examination (median 1.40 [interquartile range 1.58] vs. 0.35 [2.05]; P = 0.01). CONCLUSIONS: ANabs were associated with future development of cardiac and peripheral autonomic neuropathy in diabetic patients, implying an etiological relationship between nervous tissue autoimmunity and these diabetes complications.

Adolescent↗
PubMed2004

HLA class II polymorphisms determine responses to bacterial superantigens.

The excessive immunological response triggered by microbial superantigens has been implicated in the etiology of a wide range of human diseases but has been most clearly defined for the staphylococcal and streptococcal toxic shock syndromes. Because MHC class II presentation of superantigens to T cells is not MHC-restricted, the possibility that HLA polymorphisms could influence superantigenicity, and thus clinical susceptibility to the toxicity of individual superantigens, has received little attention. In this study, we demonstrate that binding of streptococcal and staphylococcal superantigens to HLA class II is influenced by allelic differences in class II. For the superantigen streptococcal pyrogenic exotoxin A, class II binding is dependent on DQ alpha-chain polymorphisms such that HLA-DQA1*01 alpha-chains show greater binding than DQA1*03/05 alpha-chains. The functional implications of differential binding on T cell activation were investigated in various experimental systems using human T cells and murine Vbeta8.2 transgenic cells as responders. These studies showed quantitative and qualitative differences resulting from differential HLA-DQ binding. We observed changes in T cell proliferation and cytokine production, and in the Vbeta specific changes in T cell repertoire that have hitherto been regarded as a defining feature of an individual superantigen. Our observations reveal a mechanism for the different outcomes seen following infection by toxigenic bacteria.

Amino Acid Sequence↗
PubMed2004

The development of new density gradient media for purifying human islets and islet-quality assessments.

Successful islet transplantation is dependent on the quality and quantity of islets infused. Islets are purified on density gradients, but procedures currently used have limited capacity for pancreatic digests, islet yield, and viability. We aimed to improve islet purification with a modified gradient medium. Biocoll was diluted in University of Wisconsin solution to create linear density gradients of 1.065 to 1.095 g/mL. Properties of islets purified from 22 human pancreas digests with modified medium were compared with 15 preparations using standard medium. The modification increased the capacity of gradients for pancreatic digests from 20 to 60 mL, islet yield increased from 218,000 to 435,318 per isolation, and viability increased from 65.4% to 92.1%. Islet fractions contained greater than 95% of recovered insulin. Islets showed good physiologic responses to secretagogues and restored normoglycemia in streptozotocin-induced diabetic severe combined immunodeficiency disease mice. The new medium enhances yield, purity, and viability of human islet preparations for clinical islet transplantation.

Adenosine↗
PubMed2004

Cellular immune activation in Gulf War veterans.

The etiology and pathology of illnesses related to the first Persian Gulf War are unclear. Among the constellation of symptoms noted in sick veterans, some, such as skin rashes, musculoskeletal pains, and neuropsychiatric problems, have been proposed to reflect an underlying immune dysfunction. In this study we explored the hypothesis that sickness following deployment to the Gulf in 1991 is associated with altered immune function, and we examine possible associated exposures. In particular, we focused on peripheral blood Th1/Th2 balance by measuring intracellular production of IFN-gamma, IL-2 (Th1), IL-4 (Th2), and IL-10 by CD4 T cells, using a nested case control study design within a large epidemiological survey. We compared symptomatic Gulf War veterans (sGWV) with well GWVs (wGWV), and a second control group of symptomatic veterans who served in Bosnia or were nondeployed military personnel of the same era. We found evidence for an altered immune status in sGWV in comparison to the other study groups. In particular, ongoing Th1-type immune activation was associated with multisymptom illness in GWVs, with sick veterans having significantly elevated levels of IFN-gamma and IL-2 producing CD4+ cells in the absence of in vitro stimulation compared with wGWVs (P = 0.01 and P =0.001). In vitro polyclonal activation revealed significantly elevated levels of IL-10 producing memory CD4 cells in sGWVs (P <0.001), but other cytokines were normal. In terms of possible exposures that might influence immune function, we found a trend for reduced levels of IFN-gamma producing cells after polyclonal activation with increasing numbers of vaccines administered (P <0.05) but no changes in other cytokines. These data show that multisymptom illness in Gulf War veterans is characterized by ongoing Th1-type immune activation and a biased generation of memory cells secreting the suppressor cytokine, IL-10.

Bosnia and Herzegovina↗
PubMed2004

Possession of human leucocyte antigen DQ6 alleles and the rate of CD4 T-cell decline in human immunodeficiency virus-1 infection.

Polymorphism amongst the human leucocyte antigen (HLA) class II genes could influence antigen presentation and the ability to control human immunodeficiency virus (HIV)-1 by modulating the virus specific CD4 immune response. To examine the effect of such polymorphisms on disease progression, we studied a cohort of 46 HIV-1 infected long-term non-progressors (LTNPs), 87 intermediate progressors (IPs) and 26 rapid progressors. Kaplan-Meier survival analysis of all patients in the cohort on time to a CD4 count less than 350 cells/ micro l, showed a trend for a slower rate of CD4 decline in patients with, compared to those without, the DRB1*15-DQB1*06 haplotype (hazard ratio (HR) 0.69, 95% CI 0.46-1.01, P = 0.06). A similar effect was not observed with the DRB1*13-DQB1*06 haplotype (HR 1.18, 95% CI 0.75-1.88, P = 0.46), but was observed when DQB1*06 alleles were considered irrespective of their DR association (HR 0.74, 95% CI 0.52-1.05, P = 0.06). Major HLA-DQ6 alleles encode aspartate (Asp) at position 57 on the DQbeta chain, a phenotype associated with protection from other immune disorders. We therefore examined the frequency of all DQbeta57 Asp+ alleles, but could not detect a significant effect on the rate of CD4 decline. To examine whether the genotype associated with slower CD4 decline was over-represented in patients with a slow rate of disease progression, we conducted a categorical analysis of a subset of patients with an extended follow-up of 14+years. We found a higher proportion of LTNPs at 14+ years possessed the DRB1*15-DQB1*06 haplotype compared to IPs at 14+ years (38.46 versus 18.18%), though this difference did not reach statistical significance. When DQB1*06 alleles irrespective of their DR association were considered, the protective effect was greater (76.9% LTNPs versus 18.18% IPs, P = 0.04). Our results highlight the potential protective effect of HLA DQB1*06 alleles on the course of HIV disease.

Alleles↗
PubMed2004

Identification of a naturally processed cytotoxic CD8 T-cell epitope of coxsackievirus B4, presented by HLA-A2.1 and located in the PEVKEK region of the P2C nonstructural protein.

The adaptive immune system generates CD8 cytotoxic T lymphocytes (CTLs) as a major component of the protective response against viruses. Knowledge regarding the nature of the peptide sequences presented by HLA class I molecules and recognized by CTLs is thus important for understanding host-pathogen interactions. In this study, we focused on identification of a CTL epitope generated from coxsackievirus B4 (CVB4), a member of the enterovirus group responsible for several inflammatory diseases in humans and often implicated in the triggering and/or acceleration of the autoimmune disease type 1 diabetes. We identified a 9-mer peptide epitope that can be generated from the P2C nonstructural protein of CVB4 (P2C(1137-1145)) and from whole virus by antigen-presenting cells and presented by HLA-A2.1. This epitope is recognized by effector memory (gamma interferon [IFN-gamma]-producing) CD8 T cells in the peripheral blood at a frequency of responders that suggests that it is a major focus of the anti-CVB4 response. Short-term CD8 T-cell lines generated against P2C(1137-1145) are cytotoxic against peptide-loaded target cells. Of particular interest, the epitope lies within a region of viral homology with the diabetes-related autoantigen, glutamic acid decarboxylase-65 (GAD(65)). However, P2C(1137-1145)-specific cytotoxic T lymphocyte (CTL) lines were not activated to produce IFN-gamma by the GAD(65) peptide homologue and did not show cytotoxic activity in the presence of appropriately labeled targets. These results describe the first CD8 T-cell epitope of CVB4 that will prove useful in the study of CVB4-associated disease.

Amino Acid Sequence↗
PubMed2004

Autoreactive T cell responses show proinflammatory polarization in diabetes but a regulatory phenotype in health.

According to the quality of response they mediate, autoreactive T cells recognizing islet beta cell peptides could represent both disease effectors in the development of type 1 diabetes (T1DM) and directors of tolerance in nondiabetic individuals or those undergoing preventative immunotherapy. A combination of the rarity of these cells, inadequate technology, and poorly defined epitopes, however, has hampered examination of this paradigm. We have identified a panel of naturally processed islet epitopes by direct elution from APCs bearing HLA-DR4. Employing these epitopes in a sensitive, novel cytokine enzyme-linked immunosorbent spot assay, we show that the quality of autoreactive T cells in patients with T1DM exhibits extreme polarization toward a proinflammatory Th1 phenotype. Furthermore, we demonstrate that rather than being unresponsive, the majority of nondiabetic, HLA-matched control subjects also manifest a response against islet peptides, but one that shows extreme T regulatory cell (Treg, IL-10-secreting) bias. We conclude that development of T1DM depends on the balance of autoreactive Th1 and Treg cells, which may be open to favorable manipulation by immune intervention.

Age of Onset↗
PubMed2004

Detection of autoreactive T cells in type 1 diabetes using coded autoantigens and an immunoglobulin-free cytokine ELISPOT assay: report from the fourth immunology of diabetes society T cell workshop.

The "gold standard" for evaluation of immunoassays is blinded testing, using coded samples and antigens. Although assays for autoreactive T cells are no exception to this rule, it is nonetheless rarely applied in this context. To facilitate such investigations, we coded a panel of 10 peptides representing T cell epitopes reported to be of relevance to islet autoimmunity. These were deployed in a novel cytokine ELISPOT assay, in which the use of immunoglobulin-free medium reduces background reactivity and thus potentially enhances the specificity and sensitivity of detection of autoreactive T cells. Significant IFN-gamma production against GAD65 (554-575), insulin (B9-23), and IA-2 (709-736) peptides were observed in type 1 diabetic patients, whereas no significant changes from background were detected in healthy controls. These results confirm the utility of the blinded performance of T cell assays as the most robust platform for assessing technologies to T cell autoreactivity.

Adolescent↗
PubMed2004

Enhancing the sensitivity of assays to detect T cell reactivity: the effect of cell separation and cryopreservation media.

The identification of sensitive assay formats capable of distinguishing islet autoreactive T cells directly ex vivo in blood is a major goal in type 1 diabetes research. Whereas much effort has been made to identify suitable assay formats, relatively little attention has been paid to optimizing the quality of cell preparations used. To address this issue we investigated the role of two key variables in the preparation of peripheral blood mononuclear cells (PBMCs): the separation media used in density gradient centrifugation and the method of cryopreservation. PBMCs were prepared from a single individual using different protocols and tested for responses to suboptimal concentrations of tetanus toxoid, representing a low frequency recall response. Significant differences were observed in T cell responses dependent upon the selection of the separation media and cryopreservation methods used, indicating that relatively small differences in preparation of PBMCs can have measurable effects on assay sensitivity.

Cell Proliferation↗