T-helper Cell Responses Research Articles

Heat Shock Protein 70 (HSP70) induces cytotoxicity of T-helper cells

Stress-inducible heat shock protein 70 (HSP70) has gained plenty of attention because of its potent adjuvant capability to induce antigen-specific CD8+ cytotoxic T-lymphocyte (CTL) and CD4+ T-helper cell (Th1) responses. In this study, we investigated the behavior of T-cell subsets stimulated with endotoxin-free recombinant HSP70 with respect to proliferation, cytokine expression, cytotoxicity against allogeneic B-lymphoblastoid cell line (B-LCL) and K562 cells as well as target-independent cytotoxicity. CD4+ cells exhibited a strong increase in proliferation after stimulation with HSP70, with rates of up to 29%. In the presence of target cells, a 35-fold up-regulation of granzyme B mRNA was observed after stimulation of CD4+ T-helper cells with HSP70 in combination with IL-7, -12 and -15. The target cell-independent secretion of granzyme B by CD4+ cells was greatly augmented after stimulation with HSP70 plus IL-2 or IL-7, -12 and -15. In this study, we have shown that HSP70 is capable of inducing a cytotoxic response of T-helper cells in the absence of LPS or any other PAMPs. The granzyme B secretion and the cytolytic activity of CD4+ T cells is induced in a target-independent way, whereas the cytotoxic activity of CD3+ and CD8+ T cells can be further enhanced in the presence of the target cells. Our data provide novel insights into the role of extracellular HSP70 on T-cell immune response concerning the induction of target-independent T-helper cell cytotoxicity.

Efficient Induction of HTLV-1-Specific CTL Response by HTLV-1/HBc Chimeric Particle without Adjuvant as a Prophylactic for HTLV-1- Associated T-Cell Leukemia

Adult T-cell leukemia/lymphoma (ATLL) is an aggressive peripheral T-cell neoplasm that develops only after long-term chronic infection with human T-cell leukemia virus-1 (HTLV-1). HTLV-1-specific Cytotoxic T lymphocytes (CTL) play an important role in suppressing proliferation of HTLV-1-infected or transformed T cells in vitro. The development of ATLL in approximately 2% of persons chronically infected with HTLV-1 may suggest a specific immunegenetic background predisposing to CTL failure in a proportion of HTLV-1 carriers. On the other hand, virus like particle is demonstrated to induce stronger humoral, T helper and cytotoxic T-cell responses without adjuvant. As free synthetic peptides or proteins are usually poor immunogens, the hepatitis B core (HBc) particle is a potential target carrier protein to induce immunity without use of an adjuvant. In this study, we examined the efficient induction of HTLV-1-specific CD8+ T-cell response by HTLV-1/HBc chimeric particles inserting HLA-A*0201-restricted HTLV-1 Tax-epitope without adjuvant (Figure 1). The immunization of HLA-A*0201 transgenic mice with the chimeric particle induced antigen-specific IFN-□ reaction by ELISPOT assay, whereas epitope peptide only induced no reaction (Figure 2). HTLV-1/HLA tetramer assay detected induction of HTLV-1-specific CD8+ T-cells in both splenic and inguinal lymph node cells by HTLV-1/HBc chimera particles. Furthermore, upon exposure of these dendritic cells (DCs) to the chimeric particles, the expression of CD86 was increased in a dose-dependent manner. These results suggest that HTLV-1/HBc chimeric particles are capable of inducing strong cellular immune responses without adjuvant via effective maturation of DCs and are potentially useful as an effective vaccine carrier for the treatment of cancers and infectious diseases by varying the epitope peptide. [Display omitted] [Display omitted]

Focal adhesion kinase as an immunotherapeutic target

Focal adhesion kinase (FAK) is a ubiquitously expressed non-receptor tyrosine kinase involved in cancer progression and metastasis that is found overexpressed in a large number of tumors such as breast, colon, prostate, melanoma, head and neck, lung and ovary. Thus, FAK could be an attractive tumor associated antigen (TAA) for developing immunotherapy against a broad type of malignancies. In this study, we determined whether predicted T cell epitopes from FAK would be able to induce anti-tumor immune cellular responses. To validate FAK as a TAA recognized by CD4 helper T lymphocytes (HTL), we have combined the use of predictive peptide/MHC class II binding algorithms with in vitro vaccination of CD4 T lymphocytes from healthy individuals and melanoma patients. Two synthetic peptides, FAK(143-157) and FAK(1,000-1,014), induced HTL responses that directly recognized FAK-expressing tumor cells and autologous dendritic cells pulsed with FAK-expressing tumor cell lysates in an HLA class II-restricted manner. Moreover, since the FAK peptides were recognized by melanoma patient's CD4 T cells, this is indicative that T cell precursors reactive with FAK already exist in peripheral blood of these patients. Our results provide evidence that FAK functions as a TAA and describe peptide epitopes that may be used for designing T cell-based immunotherapy for FAK-expressing cancers, which could be used in combination with newly developed FAK inhibitors.

Respiratory Syncytial Virus Persistence in Chronic Obstructive Pulmonary Disease

Respiratory syncytial virus (RSV) is predominantly recognized as a pediatric pathogen although sensitive molecular diagnostic techniques have led to its more frequent detection in some adult settings. In some studies RSV has been detected just as frequently in stable chronic obstructive pulmonary disease (COPD) patients as in those suffering disease exacerbations, leading to the suggestion that RSV may persist in COPD. Although some studies have found negligible RSV in stable COPD, others have detected RSV in one-quarter to one-third of stable COPD samples. Possible reasons for this discrepancy are explored within the article. A relationship between RSV detection and increased disease severity, including rate of decline in lung function and systemic/airway inflammation, has been found on both occasions it has been sought. Susceptibility to persistent RSV infection could involve both host and viral factors. Cigarette smoking and COPD are likely to result in impaired antiviral immunity, and RSV is capable of evading immune responses by inducing skewed type 2 T-helper cell responses, antagonizing antiviral cytokines, mimicking chemokines, inhibiting apoptosis, and entering immune-privileged cells such as pulmonary neurons. It can also escape an established immune response through antigenic drift. This article examines current evidence regarding persistence of RSV in COPD and its possible mechanisms. We also discuss various roles for RSV persistence in COPD pathogenesis. Further elucidation of the contribution of persistent RSV to the pathogenesis of COPD requires interventional studies. Persistence of RSV in COPD may have direct relevance to the pathogenesis of childhood diseases such as postbronchiolitic wheeze and asthma.

Helper T-Cell Responses and Clinical Activity of a Melanoma Vaccine With Multiple Peptides From MAGE and Melanocytic Differentiation Antigens

A phase I/II trial was performed to evaluate the safety and immunogenicity of a novel melanoma vaccine comprising six melanoma-associated peptides defined as antigenic targets for melanoma-reactive helper T cells. Source proteins for these peptides include MAGE proteins, MART-1/MelanA, gp100, and tyrosinase. Thirty-nine patients with stage IIIB to IV melanoma were vaccinated with this six-peptide mixture weekly at three dose levels, with a preceding phase I dose escalation and subsequent random assignment among the dose levels. Helper T-lymphocyte responses were assessed by in vitro proliferation assay and delayed-type hypersensitivity skin testing. Patients with measurable disease were evaluated for objective clinical response by Response Evaluation Criteria in Solid Tumors. Vaccination with the helper peptide vaccine was well tolerated. Proliferation assays revealed induction of T-cell responses to the melanoma helper peptides in 81% of patients. Among 17 patients with measurable disease, objective clinical responses were observed in two patients (12%), with response durations of 1 and 3.9+ years. Durable stable disease was observed in two additional patients for periods of 1.8 and 4.6+ years. Results of this study support the safety and immunogenicity of a vaccine comprised of six melanoma helper peptides. There is also early evidence of clinical activity.

Dysregulated expression of T-helper cell responses and susceptibility to infections in high-risk liver transplant recipients

Background Liver transplant recipients requiring dialysis have poor outcomes including higher risk of infection, and allograft rejection. The role of T-helper cell cytokine responses in the pathogenesis of infections in these patients has not been fully defined. Methods Cases were 11 dialyzed liver transplant recipients. Controls (2 for each case) were patients who were transplanted next to the case but did not require dialysis at any time before or after transplantation. Cytokine responses were assessed in sera collected immediately before transplantation. Data were analyzed for candidate cytokines for pro-inflammatory Th1 (IL-1β, IL-12p70, and IFN-γ), and Th17 (IL-12p40, IL-17), and anti-inflammatory Th2 phenotypes (IL-4, IL-5, IL-10, and IL-13). Results Cases were more likely to have an increase in any of the Th1 or Th1 and Th17 cytokines than the controls ( p = 0.016 and p = 0.04, respectively). Major infections developed in 27% of the study population; these included 46% of the cases and18%, of the controls ( p = 0.09). Patients with infections vs. those without these were more likely to have an increase in any of the Th2 cytokines ( p = 0.005). CMV viremia occurred in 30% of the patients and was significantly associated with Th1 responses even when adjusted for CMV recipient/donor serostatus or any major infection (OR 3.2, 95% CI 0.96–10.73, p = 0.05). Conclusions Requirement of dialysis was characterized by a state of heightened expression of inflammatory responses. However, patients developing infections preferentially expressed Th2 phenotype that may act as a negative regulator of protective inflammatory responses. An enhanced expression of inflammatory mediators may serve to promote CMV infection in liver transplant recipients.

Temporal Delay of Peak T-Cell Immunity DeterminesChlamydia pneumoniaePulmonary Disease in Mice

Severe chlamydial disease typically occurs after previous infections and results from a hypersensitivity response that is also required for chlamydial elimination. Here, we quantitatively dissected the immune and disease responses to repeated Chlamydia pneumoniae lung infection by multivariate modeling with four dichotomous effects: mouse strain (A/J or C57BL/6), dietary protein content (14% protein and 0.3% L-cysteine-0.9% L-arginine, or 24% protein and 0.5% L-cysteine-2.0% L-arginine), dietary antioxidant content (90 IU alpha-tocopherol/kg body weight versus 450 IU alpha-tocopherol/kg and 0.1% g L-ascorbate), and time course (3 or 10 days postinfection). Following intranasal C. pneumoniae challenge, C57BL/6 mice on a low-protein/low-antioxidant diet, but not C57BL/6 mice on other diets or A/J mice, exhibited profoundly suppressed early lung inflammatory and pan-T-cell (CD3delta(+)) and helper T-cell (CD45) responses on day 3 but later strongly exacerbated disease on day 10. Contrast analyses characterized severe C. pneumoniae disease as being a delayed-type hypersensitivity (DTH) response with increased lung macrophage and Th1 cell marker transcripts, increased Th1:Th2 ratios, and Th1 cytokine-driven inflammation. Results from functional analyses by DTH, enzyme-linked immunospot, and immunohistofluorescence assays were consistent with the results obtained by transcript analysis. Thus, chlamydial disease after secondary infection is a temporal dysregulation of the T-cell response characterized by a profoundly delayed T-helper cell response that results in a failure to eliminate the pathogen and provokes later pathological Th1 inflammation. This delayed T-cell response is under host genetic control and nutritional influence. The mechanism that temporally and quantitatively regulates the host T-cell population is the critical determinant in chlamydial pathogenesis.

Reduced HIV-stimulated T-helper cell reactivity in cord blood with short-course antiretroviral treatment for prevention of maternal-infant transmission.

T-helper cell responses to HIV have been associated with protection against maternal-infant HIV transmission in the absence of antiretroviral treatment, but the effects of antiretroviral treatment, now widely used for prevention, on development of these cell-mediated responses is unknown. We tested whether development of T-helper cell responses to HIV and other antigens would be affected by exposure to short-course regimens of zidovudine-lamivudine (ZDV-3TC) given to prevent maternal-infant HIV transmission. Cord blood samples were collected from 41 infants of HIV-infected mothers enrolled in a clinical trial in which they were treated with regimens of ZDV-3TC and from 29 infants whose HIV-infected mothers were not treated with any antiretroviral drugs. T-helper cell reactivity to HIV envelope peptides and other antigens was measured in vitro using a sensitive culture supernatant titration assay based on IL-2-dependent proliferation. Infants in the clinical trial were followed to 18 months to determine their HIV infection status, and venous blood samples were re-tested at 4.5 and 9 months for T-cell reactivity to HIV. HIV-stimulated T-helper cell reactivity in cord blood was detected 10-fold less frequently among those exposed to antiretroviral prophylaxis (2.4%) than among those unexposed (24.1%) (P = 0.007). Reductions in HIV-stimulated responses in cord blood occurred despite detectable HIV RNA (mean 3.38 standard deviation 0.76 log(10) copies per ml) at delivery among treated women and occurred independent of treatment duration. Our results suggest that short-course antiretroviral treatment given to prevent maternal-infant HIV transmission may attenuate HIV-stimulated T-cell memory responses in the neonate.

Helicobacter pylori‐Pulsed Dendritic Cells Induce H. pylori‐Specific Immunity in Mice

The growing concern over the emergence of antibiotic-resistant Helicobacter pylori infection is propelling the development of an efficacious vaccine to control this highly adaptive organism. We studied the use of a dendritic cell (DC)-based vaccine against H. pylori infection in mice. The cellular immune responses to murine bone marrow-derived DCs pulsed with phosphate-buffered saline (PBS-DC) or live H. pylori SS1 (HP-DC) were assessed in vitro and in vivo. The protective immunity against H. pylori SS1 oral challenge was compared between HP-DC or PBS-DC immunized mice. The effect of regulatory T-cell (Treg) depletion by anti-CD25 antibody on HP-DC vaccine efficacy was also evaluated. HP-DC induced a Th1-dominant response in vitro. In vivo, HP-DC immunized mice were characterized by a mixed Th1/Th2 peripheral immune response. However, in the stomach, HP-DC immunized mice expressed a higher level of IFN-gamma compared to PBS-DC immunized mice; no difference was found for interleukin-5 expressions in the stomach. A lower bacterial colonization post-H. pylori challenge was observed in HP-DC immunized mice compared to PBS-DC immunized mice with no significant difference in gastritis severity. H. pylori-specific Th1 response and protective immunity were further enhanced in vivo by depletion of Treg with anti-CD25 antibody. DC-based anti-H. pylori vaccine induced H. pylori-specific helper T-cell responses capable of limiting bacterial colonization. Our data support the critical role of effector cellular immune response in the development of H. pylori vaccine.

Comprehensive analysis of HLA-A, HLA-B, HLA-C, HLA-DRB1, and HLA-DQB1 loci and squamous cell cervical cancer risk.

Variation in human major histocompatibility genes may influence the risk of squamous cell cervical cancer (SCC) by altering the efficiency of the T-cell-mediated immune response to human papillomavirus (HPV) antigens. We used high-resolution methods to genotype human leukocyte antigen (HLA) class I (A, B, and Cw) and class II (DRB1 and DQB1) loci in 544 women with SCC and 542 controls. Recognizing that HLA molecules are codominantly expressed, we focused on co-occurring alleles. Among 137 allele combinations present at >5% in the case or control groups, 36 were significantly associated with SCC risk. All but one of the 30 combinations that increased risk included DQB1*0301, and 23 included subsets of A*0201-B*4402-Cw*0501-DRB1*0401-DQB1*0301. Another combination, B*4402-DRB1*1101-DQB1*0301, conferred a strong risk of SCC (odds ratio, 10.0; 95% confidence interval, 3.0-33.3). Among the six combinations that conferred a decreased risk of SCC, four included Cw*0701 or DQB1*02. Most multilocus results were similar for SCC that contained HPV16; a notable exception was A*0101-B*0801-Cw*0701-DRB1*0301-DQB1*0201 and its subsets, which were associated with HPV16-positive SCC (odds ratio, 0.5; 95% confidence interval, 0.3-0.9). The main multilocus associations were replicated in studies of cervical adenocarcinoma and vulvar cancer. These data confirm that T helper and cytotoxic T-cell responses are both important cofactors with HPV in cervical cancer etiology and indicate that co-occurring HLA alleles across loci seem to be more important than individual alleles. Thus, certain co-occurring alleles may be markers of disease risk that have clinical value as biomarkers for targeted screening or development of new therapies.

Antigen structure influences helper T‐cell epitope dominance in the human immune response to HIV envelope glycoprotein gp120

The development of an effective vaccine against HIV/AIDS has been hampered, in part, by a poor understanding of the rules governing helper T-cell epitope immunodominance. Studies in mice have shown that antigen structure modulates epitope immunodominance by affecting the processing and subsequent presentation of helper T-cell epitopes. Previous epitope mapping studies showed that the immunodominant helper T-cell epitopes in mice immunized with gp120 were found flanking flexible loops of the protein. In this report, we show that helper T-cell epitopes against gp120 in humans infected with HIV are also found flanking flexible loops. Immunodominant epitopes were found to be located primarily in the outer domain, an average of 12 residues C-terminal to flexible loops. In the less immunogenic inner domain, epitopes were found an average of five residues N-terminal to conserved regions of the protein, once again placing the epitopes C-terminal to flexible loops. These results show that antigen structure plays a significant role in the shaping of the helper T-cell response against HIV gp120 in humans. This relationship between antigen structure and helper T-cell epitope immunodominance may prove to be useful in the development of rationally designed vaccines against pathogens such as HIV.

Th1 biased response to a novel Porphyromonas gingivalis protein aggravates bone resorption caused by this oral pathogen

In previous studies we showed that biasing the immune response to Porphyromonas gingivalis antigens to the Th1 phenotype increases inflammatory bone resorption caused by this organism. Using a T cell screening strategy we identified eight P. gingivalis genes coding for proteins that appear to be involved in T-helper cell responses. In the present study, we characterized the protein encoded by the PG_1841 gene and evaluated its relevance in the bone resorption caused by P. gingivalis because subcutaneous infection of mice with this organism resulted in the induction of Th1 biased response to the recombinant PG1841 antigen molecule. Using an immunization regime that strongly biases toward the Th1 phenotype followed by challenge with P. gingivalis in dental pulp tissue, we demonstrate that mice pre-immunized with rPG1841 developed severe bone loss compared with control immunized mice. Pre-immunization of mice with the antigen using a Th2 biasing regime resulted in no exacerbation of the disease. These results support the notion that selected antigens of P. gingivalis are involved in a biased Th1 host response that leads to the severe bone loss caused by this oral pathogen.

Self-Tolerance Does Not Restrict the CD4+ T-Helper Response against the p53 Tumor Antigen

Tumorigenesis is frequently associated with mutation and overexpression of p53, which makes it an attractive target antigen for T cell-mediated immunotherapy of cancer. However, the magnitude and breadth of the p53-specific T-cell repertoire may be restricted due to the ubiquitous expression of wild-type p53 in normal somatic tissues. In view of the importance of the CD4+ T-helper cell responses in effective antitumor immunity, we have analyzed and compared the p53-specific reactivity of this T cell subset in p53+/+ and p53-/- C57Bl/6 mice. This response was found to be directed against the same three immunodominant epitopes in both mouse types. Fine-specificity, magnitude, and avidity were not affected by self-tolerance. Immunization of p53-/- and p53+/+ mice with synthetic peptide vaccines comprising the identified epitopes induced equal levels of Th1 immunity. Our findings imply that the p53-specific CD4+ T-cell repertoire is not restricted by self-tolerance and is fully available for the targeting of cancer.

Induction of EBV–Latent Membrane Protein 1–Specific MHC Class II–Restricted T-Cell Responses against Natural Killer Lymphoma Cells

EBV-encoded latent membrane protein 1 (LMP1) has oncogenic potential and is expressed in many EBV-associated malignancies. Although LMP1 is regarded as a potential tumor-associated antigen for immunotherapy and several LMP1-specific MHC class I-restricted CTL epitopes have been reported, little is known regarding MHC class II-restricted CD4 helper T-lymphocyte (HTL) epitopes for LMP1. The goal of the present studies was to determine whether MHC class II-restricted CD4 T-cell responses could be induced against the LMP1 antigen and to evaluate the antitumor effect of these responses. We have combined the use of a predictive MHC class II binding peptide algorithm with in vitro vaccination of CD4 T cells using candidate peptides to identify naturally processed epitopes derived from LMP1 that elicit immune responses against EBV-expressing tumor cells. Peptide LMP1(159-175) was effective in inducing HTL responses that were restricted by HLA-DR9, HLA-DR53, or HLA-DR15, indicating that this peptide behaves as a promiscuous T-cell epitope. Moreover, LMP1(159-175)-reactive HTL clones directly recognized EBV lymphoblastoid B cells, EBV-infected natural killer (NK)/T-lymphoma cells and naturally processed antigen in the form of LMP1+ tumor cell lysates presented by autologous dendritic cells. Because the newly identified epitope LMP1(159-175) overlaps with an HLA-A2-restricted CTL epitope (LMP1(159-167)), this peptide might have the ability to induce simultaneous CTL and HTL responses against LMP1. Overall, our data should be relevant for the design and optimization of T-cell epitope-based immunotherapy against various EBV-associated malignancies, including NK/T cell lymphomas.

CpG increases vaccine antigen-specific cell-mediated immunity when administered with hepatitis B vaccine in HIV infection

BackgroundLack of adequate adjuvancy is a possible explanation for lack of vaccine immunogenecity. Immunostimulatory CpGs are potent vaccine adjuvants and may be an important component of the development vaccines, particularly those for which a cellular immune response is required for protection. We have previously demonstrated that CpG ODN co-administration with hepatitis B vaccine results in earlier, stronger and more sustained antibody responses to hepatitis B surface antigen in HIV infected individuals, and wished to determine if, in this population, helper T-cell responses were also enhanced.MethodsWe conducted a double-blind, placebo-controlled trial in hepatitis B susceptible, effectively treated HIV-seropositive individuals. Participants received hepatitis B vaccine, with either placebo or CPG 7909 1.0 mg at week 0, 4 and 8. To determine the impact of CpG on cellular immune responses, lymphoproliferative responses (LPR) were evaluated by [3H]-thymidine incorporation at baseline and weeks 4, 8, 12, 24, and 48. Immunophenotyping of lymphocyte subsets was also determined at these time points.ResultsOf 36 patients enrolled, 18 received hepatitis B vaccine alone, and 18 received hepatitis B vaccine with CpG. Inclusion of CPG 7909 was associated with a greater proliferative response to HBsAg at all time points following initial vaccination. This increase was statistically significant at 8 weeks (p = 0.042) and 48 weeks (p = 0.024). Similar results were observed when LPR were evaluated as stimulation indices (SI). No differences in proliferative responses to HIV p24 Ag were observed, nor were there any differences in lymphocyte subsets.ConclusionIn addition to enhancing humoral responses to vaccination, we describe for the first time that CPG 7909 enhances cellular immunity to vaccine antigen in a typically hyporesponsive population. This adjuvancy may be important in the development of an effective vaccine for which a cellular immune response is required for protection.

Bacillus Calmette-Guerin in the management of superficial bladder cancer

Intravesical Bacillus Calmette-Guérin (BCG) is the mainstay of superficial bladder cancer treatment. We performed a literature search through Medline/Pubmed using key words ‘Bacillus Calmette-Guérin’, ‘intravesical’, ‘bladder neoplasm’ and ‘immunotherapy’ for published data in the English language from 1970 to 2007 to review the current status of intravesical therapy and practice recommendations. The exact mechanism of action of intravesical BCG is yet to be elucidated. However, it appears that it is mediated by the local immune response, mainly through T-helper cell response. It reduces the recurrence rate by an average of 40% and progression by more than 20% in papillary tumors over the patients without BCG therapy. However, progression prevention is seen only in series which have used maintenance therapy at least for one year. It is effective in CIS of bladder with a response rate of more than 40% and prevention of progression in one-fourth patients. Most acceptable dose, induction treatment and maintenance therapy protocols are discussed. However, these are yet to be confirmed in large randomized trials. Intravesical BCG is well tolerated in most of the patients with mild to moderate side-effects in induction therapy; however, most patients do not complete maintenance therapy due to side-effects which is the most common concern at the present time.

The “T” in Trauma: the Helper T-cell Response and the Role of Immunomodulation in Trauma and Burn Patients

The immune system undergoes numerous changes after traumatic and burn injuries, including a down-regulation of the TH1 response and up-regulation of the TH2 response. The PubMed, Medline, and Ovid search engines were queried for relevant human studies. Bibliographies were also meticulously reviewed. An interesting and potentially clinically relevant pattern of immune dysregulation exists after injury. The type 1 T-helper cell (TH1) response is suppressed as illustrated by diminished interleukin (IL)-2, interferon (IFN)-gamma, and IL-12 levels after major injury. The enhancement of the TH2 response is marked by elevated IL-10 and IL-4. Certain cytokine profiles, ratios, and polymorphisms may help identify patients at increased risk of systemic inflammatory response syndrome (SIRS), sepsis, multiple organ failure (MOF), and deep venous thrombosis. The most promising prognostic indicators to date are decreased production of the IL-12, elevated IL-10, soluble IL-2 receptor-a (sIL-2Ra), and IL-18 levels, IL-18 promoter polymorphisms, the IL-6:IL-10 ratio, and the degree of TH1 suppression as measured by diminished IL-2 and IFN-gamma. The Cytokine sections are subdivided into basic science, human studies, animal studies (when necessary), and directed therapeutics. The outcomes of sepsis, SIRS, or MOF are generally discussed together. T-cell-specific immunologic changes occur after major injury. Identification of those TH1/TH2 cytokine profiles associated with worse prognosis may one day allow clinicians to risk stratify injured patients and identify those at increased risk of developing SIRS, sepsis, MOF, and deep venous thrombosis. Immune-targeted therapies may eventually serve as effective treatments in the acute setting to decrease morbidity and mortality, and to improve the management and prognosis of those patients at risk for developing postinjury complications.

Dietary Melibiose Regulates Th Cell Response and Enhances the Induction of Oral Tolerance

We examined how dietary melibiose affected the T-helper (Th) cell responses induced by an orally fed antigen in ovalbumin (OVA)-specific T cell receptor transgenic mice (OVA 23-3). Dietary melibiose markedly decreased the Th2 type responses as shown by a significant decrease in the interleukin (IL)-4 production and T cell proliferative response induced by sensitization from the 7-d oral administration of OVA. It was additionally observed that the Th1 type responses tended to decrease. We therefore examined the effect of melibiose feeding on the induction of immunological tolerance induced by the oral administration of an antigen (oral tolerance). The Th cell responses induced in BALB/c mice by subcutaneous immunization with OVA were suppressed by the prior oral administration of OVA. Such responses in the OVA-fed and immunized mice were further diminished by dietary melibiose. These results suggest that dietary melibiose strongly affected the Th cell responses to an ingested antigen, and further demonstrate the potential of melibiose to enhance the induction of oral tolerance.

Naïve Donor Responses to Schistosoma mansoni Soluble Egg Antigens

Schistosome infection induces profound Th-biasing and immune suppression. Although much has been examined in mice, few studies have examined responses of naïve humans to schistosome antigens. In this study, we examined the response of naïve human peripheral blood mononuclear cells (nPBMC) to stimulation with Schistosoma mansoni soluble egg antigen (SEA) using a priming in vitro (PIV) assay. We found that SEA induced a pronounced CD4+ T-helper cell response based on cytokine secretion and phenotyping markers. SEA-stimulated nPBMC (SEA cells) at day 7 post-priming and after the first recall consisted predominantly of Th0-like CD4+ T cells. Following the second recall, the majority of donor (10/12) responses were Th2-like. The cell population consisted of approximately 64% CD4+, 17% CD8(+high), 12% CD19+, and 7% CD23+ cells. The CD4+ population also expressed HLA-DR+, CD54+, CD45RO+ and CD25+ whereas the CD19+ cells expressed CD80 and CD86. Following priming, we detected high levels of IL-6, IFN-gamma, IL-12p40, IL-10 and IL-5. Upon restimulation, SEA cells secreted IL-5 and high levels of IL-10, typical of a Th2-like response. The data presented herein shows that the majority of naïve donor dendritic cells, following stimulation with SEA, prime and clonally expand SEA-specific T cells towards a Th2-type response. However, two donors responded with an atypical response, producing IFN-gamma coincident with low levels of IL-10. Whether this differential response was due to HLA or other genes was not determined but is currently under investigation.

Rational design of a multiepitope vaccine encoding T-lymphocyte epitopes for treatment of chronic hepatitis B virus infections.

Protein sequences from multiple hepatitis B virus (HBV) isolates were analyzed for the presence of amino acid motifs characteristic of cytotoxic T-lymphocyte (CTL) and helper T-lymphocyte (HTL) epitopes with the goal of identifying conserved epitopes suitable for use in a therapeutic vaccine. Specifically, sequences bearing HLA-A1, -A2, -A3, -A24, -B7, and -DR supertype binding motifs were identified, synthesized as peptides, and tested for binding to soluble HLA. The immunogenicity of peptides that bound with moderate to high affinity subsequently was assessed using HLA transgenic mice (CTL) and HLA cross-reacting H-2(bxd) (BALB/c x C57BL/6J) mice (HTL). Through this process, 30 CTL and 16 HTL epitopes were selected as a set that would be the most useful for vaccine design, based on epitope conservation among HBV sequences and HLA-based predicted population coverage in diverse ethnic groups. A plasmid DNA-based vaccine encoding the epitopes as a single gene product, with each epitope separated by spacer residues to enhance appropriate epitope processing, was designed. Immunogenicity testing in mice demonstrated the induction of multiple CTL and HTL responses. Furthermore, as a complementary approach, mass spectrometry allowed the identification of correctly processed and major histocompatibility complex-presented epitopes from human cells transfected with the DNA plasmid. A heterologous prime-boost immunization with the plasmid DNA and a recombinant MVA gave further enhancement of the immune responses. Thus, a multiepitope therapeutic vaccine candidate capable of stimulating those cellular immune responses thought to be essential for controlling and clearing HBV infection was successfully designed and evaluated in vitro and in HLA transgenic mice.