Enzyme-linked Immunosorbent Spot Research Articles

Diagnostic value of an IFN-γ ELISPOT assay to detect latent tuberculosis infection in hepatitis C patients

The rapid diagnosis of tuberculosis (TB) and latent tuberculosis infections (LTBI) is a significant problem in clinical practice. The aim of this study was to evaluate the diagnostic value of an enzyme-linked immunosorbent spot (ELISPOT) assay measuring interferon-γ in hepatitis C patients with LTBI. A total of 160 hepatitis C patients at the Jilin University Hospital, Changchun, China, were prospectively enrolled from January 2009 to December 2010; 43 had been positively diagnosed with TB, 38 with non-TB diseases, and 79 with a history of TB. All patients were evaluated by the tuberculin skin test (TST) and ELISPOT assays. Among the 43 diagnosed TB patients, the ELISPOT assay had a sensitivity of 92.1%, compared to a sensitivity of 60.5% for the TST. Among the 79 TB exposure patients, the ELISPOT assay was more sensitive (90%) than the TST (61.5%), the specificity of the ELISPOT assay was 90%, and the specificity of the TST was 61.5% in LTBI. Among the 38 subjects with non-TB diseases, the specificity of the ELISPOT was better than the TST’s. In conclusion, this ELISPOT assay could provide useful support in diagnosing LTBI in hepatitis C patients and may provide guidance regarding the treatment of LTBI and hepatitis C co-infection. Key words: Latent tuberculosis infections (LTBI), Hepatitis C virus (HCV), enzyme-linked immunosorbent spot (ELISPOT) assay, CFP-10/ESAT-6

Widespread impact of HLA restriction on immune control and escape pathways of HIV-1.

The promiscuous presentation of epitopes by similar HLA class I alleles holds promise for a universal T-cell-based HIV-1 vaccine. However, in some instances, cytotoxic T lymphocytes (CTL) restricted by HLA alleles with similar or identical binding motifs are known to target epitopes at different frequencies, with different functional avidities and with different apparent clinical outcomes. Such differences may be illuminated by the association of similar HLA alleles with distinctive escape pathways. Using a novel computational method featuring phylogenetically corrected odds ratios, we systematically analyzed differential patterns of immune escape across all optimally defined epitopes in Gag, Pol, and Nef in 2,126 HIV-1 clade C-infected adults. Overall, we identified 301 polymorphisms in 90 epitopes associated with HLA alleles belonging to shared supertypes. We detected differential escape in 37 of 38 epitopes restricted by more than one allele, which included 278 instances of differential escape at the polymorphism level. The majority (66 to 97%) of these resulted from the selection of unique HLA-specific polymorphisms rather than differential epitope targeting rates, as confirmed by gamma interferon (IFN-γ) enzyme-linked immunosorbent spot assay (ELISPOT) data. Discordant associations between HLA alleles and viral load were frequently observed between allele pairs that selected for differential escape. Furthermore, the total number of associated polymorphisms strongly correlated with average viral load. These studies confirm that differential escape is a widespread phenomenon and may be the norm when two alleles present the same epitope. Given the clinical correlates of immune escape, such heterogeneity suggests that certain epitopes will lead to discordant outcomes if applied universally in a vaccine.

The clinical relevance of persistent recombinant immunoblot assay–indeterminate reactions: insights into the natural history of hepatitis C virus infection and implications for donor counseling

Recombinant immunoblot assay (RIBA) is used to determine the specificity of antibody to hepatitis C virus (anti-HCV). The RIBA result is recorded as positive, negative, or indeterminate. The interpretation and significance of RIBA-indeterminate reactions are unclear. We addressed the clinical relevance of these reactions in the context of the natural history of HCV infection in a prospectively followed cohort of anti-HCV-positive blood donors. Donor demographics, exposure history, and humoral and cell-mediated immunity (CMI) were compared in 15 RIBA-indeterminate subjects, nine chronic HCV carriers, and eight spontaneously recovered subjects. Serum samples were tested for anti-HCV by a quantitative, liquid luciferase immunoprecipitation system (LIPS). CMI was assessed by interferon-γ enzyme-linked immunosorbent spot assay. In the LIPS assay, the sum of antibody responses to six HCV antigens showed significant (p < 0.001) stepwise diminution progressing from chronic carriers to spontaneously recovered to RIBA-indeterminate subjects. CMI responses in RIBA-indeterminate subjects were similar to spontaneously recovered subjects and greater than chronic carriers and controls (p < 0.008). A parenteral risk factor was identified in only 13% of RIBA-indeterminate subjects compared to 89% of chronic carriers and 87% of spontaneously recovered subjects. RIBA-indeterminate donors were older than the other groups. The CMI and LIPS results suggest that persistent RIBA-indeterminate reactions represent waning anti-HCV responses in persons who have recovered from a remote HCV infection. In such cases, detectable antibody may ultimately disappear leaving no residual serologic evidence of prior HCV infection, as reported in a minority of long-term HCV-recovered subjects.

Clinical outcome of patients with various advanced cancer types vaccinated with an optimized cryptic human telomerase reverse transcriptase (TERT) peptide: results of an expanded phase II study

TERT (telomerase reverse transcriptase) plays a critical role in tumor cell growth and survival. In an expanded phase II study, we evaluated the immunological and clinical responses to the TERT-targeting Vx-001 vaccine in patients with advanced solid tumors. HLA-A*0201-positive patients received two subcutaneous injections of the optimized TERT(572Y) peptide followed by four injections of the native TERT(572) peptide, every 3 weeks. Peptide-specific immune responses were evaluated by enzyme-linked immunosorbent spot at baseline, and after the second and the sixth vaccinations. Fifty-five patients were enrolled and 34 (62%) completed the six vaccinations. A TERT-specific T-cell immune response was observed in 55% and 70% of patients after the second and the sixth vaccinations, respectively. The disease control rate (DCR) was 36% [95% confidence interval (CI) 24% to 49%], including one complete and one partial response. Immunologically responding patients had a better clinical outcome than nonresponders [DCR: 44% versus 14% (P = 0.047); progression-free survival (PFS): 5.2 versus 2.2 months (P = 0.0001) and overall survival: 20 versus 10 months (P = 0.041)]. Multivariate analysis revealed that the immunological response was an independent variable associated with increased PFS (hazard ratio = 3.35; 95% CI 1.7-6.7). Vx-001 vaccine was well tolerated and induced a TERT-specific immunological response, which was significantly correlated with improved clinical outcome.

Arthritis development in germ free mice deficient for reactive oxygen species

BackgroundThe Ncf1 protein is a subunit of the nicotinamide adenine dinucleotide phosphate oxidase (NADPH) oxidase complex, which is responsible for producing the precursors of reactive oxygen species (ROS). ROS is...

Investigation and Treatment of a Complicated Inflammatory Aortoiliac Aneurysm

Inflammatory abdominal aortic aneurysms (IAAAs) account for 5% to 10% of all abdominal aortic aneurysms, occurring primarily in males. Their true etiology is unknown. Symptoms and signs of IAAA are so variable that they present to a wide range of specialties. There is debate in the literature whether IAAA is a manifestation of systemic autoimmune disease. We describe the case of a young female patient with complicated inflammatory aortoiliac aneurysmal disease, illustrating diagnostic and treatment challenges that remain. Our patient had a positive autoantibody screen, raised erythrocyte sedimentation rate, positive enzyme-linked immunosorbent spot test, and saccular aneurysms, including infective and inflammatory etiologies in her differential diagnosis. Early diagnosis is crucial to limit disease progression, morbidity, and mortality. Medical management is important to address the underlying disease process, but a combination of endovascular and open surgical intervention is often necessary for definitive treatment. Available evidence offers plausibility for benefit of endovascular intervention over open repair.

Inhibition of renin angiotensin aldosterone system causes abrogation of obliterative airways disease through inhibition of tumor necrosis factor-α–dependant interleukin-17

Alloimmune-induced immune responses to self-antigens are involved in the development of chronic lung allograft rejection. Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) have been shown to modulate autoimmune diseases. This study investigated the effect of modulation of the renin angiotensin aldosterone system (RAAS) a murine model of obliterative airways disease (OAD). Major histocompatibility complex (MHC) class I antibodies were administered intrabronchially to C57Bl/6 mice on Days 1, 2, 3, and 6, and weekly thereafter. ACEI/ARB (10 mg/kg/day) were administered in water 5 days before antibody administration. Antibodies were analyzed by enzyme-linked immunosorbent assay, cytokines by Luminex, Th-frequency by enzyme-linked immunosorbent spot, and transcription factors by Western blotting and real-time polymerase chain reaction. Significant decreases (50%-70%) in airway lesions and fibrous deposition were noted in lungs at Day 30 in the animals administered ACEI and ARB vs controls. Antibody concentrations to self-antigens also decreased from 14 ± 21 to 62 ± 18 μg/ml for collagen V and from 263 ± 43 to 84 ± 28 μg/ml for K-α1 tubulin. Th-precursor frequency and cytokine analysis showed increased interleukin (IL)-10 (3-fold increase) and decreased levels of IL-6 (3.4-fold) and IL-17 (4-fold decrease; p < 0.05) in ACEI and ARB groups. There was also messenger RNA level downregulation of tumor necrosis factor-α (8.6-fold) and p38/mitogen-activated protein (MAP)kinase (3.1-fold) in the treatment groups. Our results demonstrate that modulation of RAAS leads to downregulation of IL-17 through tumor necrosis factor-α-dependant IL-6 through p38/MAPKinase pathway and thus abrogation of anti-MHC-induced OAD.

CD8+T Cells Provide an Immunologic Signature of Tuberculosis in Young Children

The immunologic events surrounding primary Mycobacterium tuberculosis infection and development of tuberculosis remain controversial. Young children who develop tuberculosis do so quickly after first exposure, thus permitting study of immune response to primary infection and disease. We hypothesized that M. tuberculosis-specific CD8(+) T cells are generated in response to high bacillary loads occurring during tuberculosis. To determine if M. tuberculosis-specific T cells are generated among healthy children exposed to M. tuberculosis and children with tuberculosis. Enzyme-linked immunosorbent spot assays were used to measure IFN-γ production in response to M. tuberculosis-specific proteins ESAT-6/CFP-10 by peripheral blood mononuclear cells and CD8(+) T cells isolated from Ugandan children hospitalized with tuberculosis (n = 96) or healthy tuberculosis contacts (n = 62). The proportion of positive CD8(+) T-cell assays and magnitude of CD8(+) T-cell responses were significantly greater among young (<5 yr) tuberculosis cases compared with young contacts (P = 0.02, Fisher exact test, P = 0.01, Wilcoxon rank-sum, respectively). M. tuberculosis-specific T-cell responses measured in peripheral blood mononuclear cells were equivalent between groups. Among young children, M. tuberculosis-specific CD8(+) T cells develop in response to high bacillary loads, as occurs during tuberculosis, and are unlikely to be found after M. tuberculosis exposure. T-cell responses measured in peripheral blood mononuclear cells are generated after M. tuberculosis exposure alone, and thus cannot distinguish exposure from disease. In young children, IFN-γ-producing M. tuberculosis-specific CD8(+) T cells provide an immunologic signature of primary M. tuberculosis infection resulting in disease.

Monitoring of peptide-specific and gamma interferon-productive T cells in patients with active and convalescent tuberculosis using an enzyme-linked immunosorbent spot assay.

To establish a high-efficiency gamma interferon-specific enzyme-linked immunosorbent spot assay (IFN-γ ELISPOT assay) for detection of tuberculosis (TB), peptides (E6, E7, and C14) and peptide mixtures (E6 plus E7 and E6 plus E7 plus C14) were used to monitor peripheral blood (PBL) samples from patients with pulmonary TB (PTB), as well as control samples. The positive detection rates of the five IFN-γ ELISPOT assays were 78.38%, 74.86%, 55.83%, 90.43%, and 91.51%, respectively, and there were similar detection rates between the two combined peptide mixture IFN-γ ELISPOT assays and the tuberculin skin test (TST) (90.62% versus 95.59%). No significant difference was found between the detection rates of the two combined peptide mixture IFN-γ ELISPOT assays and the T-SPOT.TB assay for 86 patients with PTB (P > 0.05), but the median number of spot-forming cells/10(6) cells (SFP value) for positive results was higher by the former than by the latter assay (P < 0.05). In contrast, the 29.93% positive detection rate and median SFP value of 482 by the two combined peptide mixture IFN-γ ELISPOT assays were significantly higher than the corresponding values of 14.29% and 152 by T-SPOT.TB assay for the same 147 community donors (P < 0.05). For nine PTB patients tracked, the SFP value of 7 for the two peptide mixture IFN-γ ELISPOT assays began to decrease from the second month after regular treatment. A relatively low, almost normal, SFP level was reached and maintained after the third or fourth month. Two in-house IFN-γ ELISPOT assays and the T-SPOT.TB assay could reduce the false-positive and false-negative detection rates of TST and sputum acid-fast staining. Therefore, these two combined peptide mixture IFN-γ ELISPOT assays have a potential advantage, beyond their greater specificity and sensitivity, for use in screening and detection of active TB infection (TBI) and latent TB infection (LTBI) in China.

Expression of Interleukin-8 Receptor CXCR2 and Suppressor of Cytokine Signaling-3 in Astrocytic Tumors

The aim was to expand recently published information regarding the significance of the interleukin (IL)-8/p-STAT-3 (signal transducer and activator of transcription) pathway in astrocytomas, focusing on the IL-8 receptor, chemokine (C-X-C motif) receptor 2 (CXCR2), and the STAT-3 inhibitor SOCS-3 (suppressors of cytokine signaling). A total of 91 paraffin-embedded human astrocytoma tissues (grades II-IV) were investigated for the association of SOCS-3 and CXCR2 expression with clinicopathologic and morphometric microvascular characteristics, vascular endothelial growth factor (VEGF), IL-8 and p-STAT-3 expression and patient survival. Peripheral IL-8 secretion levels were assessed by enzyme-linked immunosorbent spot (ELISPOT). SOCS-3, p-STAT-3 and CXCR2 protein levels were also quantified by Western immunoblotting in six cases, and the protein levels of SOCS-3 and CXCR2 were correlated with the immunohistochemical expression of the respective proteins. All CXCR2-positive cases by Western immunoblotting displayed increased peripheral IL-8 secretion levels. Treatment of primary glioblastoma cell cultures with exogenous IL-8 enhanced proliferation, and this effect was inhibited by treatment with a neutralizing anti-CXCR2 antibody. SOCS-3 and CXCR2 were expressed by neoplastic astrocytes in 92.4% and 48.78% of cases, respectively, with their levels increasing with histological grade and extent of necrosis. VEGF expression and microvessel density, CXCR2 and IL-8 levels were interrelated. SOCS-3 and p-STAT-3 were co-expressed in 85.7% of cases, although they were not interrelated. In univariate survival analysis, increased SOCS-3 expression and the presence of CXCR2 adversely affected survival, whereas in multivariate analysis, only CXCR2 remained significant. The prognostic significance of CXCR2 was validated in an independent set of 63 patients. Our data implicate IL-8/CXCR2 signaling pathway in the progression and regulation of angiogenesis in astrocytomas and provide a rationale for CXCR2 therapeutic exploitation in these tumors.

Involvement of intron A into eukaryotic expression vector to improve immunogenicity of mycobacterial heat-shock protein 65 DNA vaccine in mice

To explore the involvement of intron A into eukaryotic expression vector to improve antigen expression efficiency and enhance immunogenicity of DNA vaccine in mice. As model antigen, the coding gene of mycobacterial Hsp65 was cloned into eukaryotic expression vector pCMV4.0 with intron A involved and pVAX1 without intron A involved, respectively. The resulted recombinant expression vectors were transfected into 293T cells and were then injected into BALB/c mice as DNA vaccines. Anti-Hsp65 specific IgG and isotype were detected by ELISA and T cell immune response was analyzed by enzyme-linked immunosorbent spot (ELISPOT) assay and intracellular cytokine staining. Compared with non-intron A pVAX1hsp65, the recombinant plasmid pCMV4.0hsp65 involved with intron A pVAX1hsp65 caused higher expression level of Hsp65 in 293T cells, and enhanced Th1 type immune response, which was defined as higher level of anti-Hsp65 specific total IgG level (3.76 ± 0.23 vs 3.15 ± 0.22, P < 0.01) and IgG2a/IgG1 ratio (4.08 ± 0.04 vs 2.23 ± 0.12, P < 0.01) and more IFN-γ-secreting CD4(+) ((2.0 ± 0.058)% vs (1.5 ± 0.087)%, t = 4.804, P < 0.01) and CD8(+) ((0.6 ± 0.058)% vs (1.0 ± 0.115)%, t = 3.098, P < 0.05) T lymphocytes. The difference showed statistical significance. Intron A can improve the expression efficiency of mycobacterial Hsp65 antigen and enhance immunogenicity of DNA vaccine in mice when involved into eukaryotic expression vector.

Vaccination with dendritic cells pulsed with hepatitis C pseudo particles induces specific immune responses in mice.

To explore dendritic cells (DCs) multiple functions in immune modulation. We used bone-marrow derived dendritic cells from BALB/c mice pulsed with pseudo particles from the hepatitis C virus to vaccinate naive BALB/c mice. Hepatitis C virus (HCV) pseudo particles consist of the genotype 1b derived envelope proteins E1 and E2, covering a non-HCV core structure. Thus, not a single epitope, but the whole "viral surface" induces immunogenicity. For vaccination, mature and activated DC were injected subcutaneously twice. Humoral and cellular immune responses measured by enzyme-linked immunosorbent assay and interferon-gamma enzyme-linked immunosorbent spot test showed antibody production as well as T-cells directed against HCV. Furthermore, T-cell responses confirmed two highly immunogenic regions in E1 and E2 outside the hypervariable region 1. Our results indicate dendritic cells as a promising vaccination model for HCV infection that should be evaluated further.

Effects of vitamin A and D receptor gene polymorphisms/haplotypes on immune responses to measles vaccine.

Vitamins A and D, and their receptors, are important regulators of the immune system, including vaccine immune response. We assessed the association between polymorphisms in the vitamin A receptors [retinoic acid receptor α, retinoic acid receptor β (RARB), and retinoic acid receptor γ] and vitamin D receptor (VDR)/retinoid X receptor α (RXRA) genes and interindividual variations in immune responses after two doses of measles vaccine in 745 children. Using a tag single nucleotide polymorphism (SNP) approach, we genotyped 745 healthy children for the 391 polymorphisms in vitamin A receptor and VDR genes. The RARB haplotype (rs6800566/rs6550976/rs9834818) was significantly associated with variations in both measles antibody (global, P=0.013) and cytokine secretion levels, such as interleukin (IL)-10 (global, P=0.006), interferon (IFN)-α (global, P=0.008), and tumor necrosis factor-α (global, P=0.039) in the Caucasian subgroup. Specifically, the RARB haplotype, AAC, was associated with higher (t-statistic: 3.27, P=0.001) measles antibody levels. At the other end of the spectrum, haplotype GG for rs6550978/rs6777544 was associated with lower antibody levels (t-statistic: -2.32, P=0.020) in the Caucasian subgroup. In a sensitivity analysis, the RARB haplotype, CTGGGCAA, remained marginally significant (P<0.02) when the single SNP rs12630816 was included in the model for IL-10 secretion levels. A significant association was found between lower measles-specific IFN-γ Enzyme-linked immunosorbent spot responses and haplotypes rs11102986/rs11103473/rs11103482/rs10776909/rs12004589/rs35780541/rs2266677/rs875444 (global, P=0.004) and rs6537944/rs3118571 (global, P<0.001) in the RXRA gene for Caucasians. We also found associations between multiple RARB, VDR, and RXRA SNPs/haplotypes and measles-specific IL-2, IL-6, IL-10, IFN-α, IFN-γ, IFNλ-1, and TNF-α cytokine secretions. Our results suggest that specific allelic variations and haplotypes in the vitamin A receptor and VDR genes may influence adaptive immune responses to measles vaccine.

Humoral and Cellular Immune Responses to Yersinia pestis Infection in Long-Term Recovered Plague Patients

Plague is one of the most dangerous diseases and is caused by Yersinia pestis. Effective vaccine development requires understanding of immune protective mechanisms against the bacterium in humans. In this study, the humoral and memory cellular immune responses in plague patients (n = 65) recovered from Y. pestis infection during the past 16 years were investigated using a protein microarray and an enzyme-linked immunosorbent spot assay (ELISpot). The seroprevalence to the F1 antigen in all recovered patients is 78.5%. In patients infected more than a decade ago, the antibody-positive rate still remains 69.5%. There is no difference in the antibody presence between gender, age, and infected years, but it seems to be associated with the F1 antibody titers during infection (r = 0.821; P < 0.05). Except F1 antibody, the antibodies against LcrV and YopD were detected in most of the patients, suggesting they could be the potential diagnostic markers for detecting the infection of F1-negative strains. Regarding cellular immunity, the cell number producing gamma interferon (IFN-γ), stimulated by F1 and LcrV, respectively, in vitro to the peripheral blood mononuclear cells of 7 plague patients and 4 negative controls, showed no significant difference, indicating F1 and LcrV are not dominant T cell antigens against plague for a longer time in humans. Our findings have direct implications for the future design and development of effective vaccines against Y. pestis infection and the development of new target-based diagnostics.

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

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

Sequential Administration of the Native TERT572 Cryptic Peptide Enhances the Immune Response Initiated by its Optimized Variant TERT572Y in Cancer Patients

The aim of this study was to investigate the best administration of telomerase reverse transcriptase (TERT572), an human leukocyte antigen-A*0201-restricted cryptic epitope of telomerase, and its optimized variant TERT(572Y) to elicit specific T cell immune responses in cancer patients. Forty-eight cancer patients with chemo-resistant tumors received 2 subcutaneous injections of TERT(572Y) at 2 mg followed at random by 4 subcutaneous injections of either TERT572 or TERT(572Y) peptides at 2 mg every 3 weeks. Specific immune response was evaluated by interferon-γ enzyme-linked immunosorbent spot. T cell responses after the sixth vaccination were detected more frequently (44% vs. 17%), and with higher number of peptide-specific reactive T cells (60 T cells/2 × 10(5) peripheral blood mononuclear cell vs. 10 T cells/2 × 10(5) peripheral blood mononuclear cell, P=0.04), and higher avidity in the patients who received 4 more vaccinations with the TERT572 peptide compared with patients who received only TERT(572Y) vaccinations. These results demonstrate that the best vaccination schedule involves first the administration of the optimized TERT(572Y) followed by the native TERT572 peptides in patients who are candidates for cancer immunotherapy.

Toxoplasma gondii HLA-B*0702-restricted GRA720-28 peptide with adjuvants and a universal helper T cell epitope elicits CD8+ T cells producing interferon-γ and reduces parasite burden in HLA-B*0702 mice

The ability of CD8(+) T cells to act as cytolytic effectors and produce interferon-γ (IFN-γ) was demonstrated to mediate resistance to Toxoplasma gondii in murine models because of the recognition of peptides restricted by murine major histocompatibility complex (MHC) class I molecules. However, no T gondii-specific HLA-B07-restricted peptides were proven protective against T gondii. Recently, 2 T gondii-specific HLA-B*0702-restricted T cell epitopes, GRA7(20-28) (LPQFATAAT) and GRA3(27-35) (VPFVVFLVA), displayed high-affinity binding to HLA-B*0702 and elicited IFN-γ from peripheral blood mononuclear cells of seropositive HLA-B*07 persons. Herein, these peptides were evaluated to determine whether they could elicit IFN-γ in splenocytes of HLA-B*0702 transgenic mice when administered with adjuvants and protect against subsequent challenge. Peptide-specific IFN-γ-producing T cells were identified by enzyme-linked immunosorbent spot and proliferation assays utilizing splenic T lymphocytes from human lymphocyte antigen (HLA) transgenic mice. When HLA-B*0702 mice were immunized with one of the identified epitopes, GRA7(20-28) in conjunction with a universal CD4(+) T cell epitope (PADRE) and adjuvants (CD4(+) T cell adjuvant, GLA-SE, and TLR2 stimulatory Pam(2)Cys for CD8(+) T cells), this immunization induced CD8(+) T cells to produce IFN-γ and protected mice against high parasite burden when challenged with T gondii. This work demonstrates the feasibility of bioinformatics followed by an empiric approach based on HLA binding to test this biologic activity for identifying protective HLA-B*0702-restricted T gondii peptides and adjuvants that elicit protective immune responses in HLA-B*0702 mice.

Spontaneous autoimmune gastritis and hypochlorhydria are manifest in the ileitis-prone SAMP1/YitFcs mice

SAMP1/YitFcs mice serve as a model of Crohn's disease, and we have used them to assess gastritis. Gastritis was compared in SAMP1/YitFcs, AKR, and C57BL/6 mice by histology, immunohistochemistry, and flow cytometry. Gastric acid secretion was measured in ligated stomachs, while anti-parietal cell antibodies were assayed by immunofluorescence and enzyme-linked immunosorbent spot assay. SAMP1/YitFcs mice display a corpus-dominant, chronic gastritis with multifocal aggregates of mononuclear cells consisting of T and B lymphocytes. Relatively few aggregates were observed elsewhere in the stomach. The infiltrates in the oxyntic mucosa were associated with the loss of parietal cell mass. AKR mice, the founder strain of the SAMP1/YitFcs, also have gastritis, although they do not develop ileitis. Genetic studies using SAMP1/YitFcs-C57BL/6 congenic mice showed that the genetic regions regulating ileitis had comparable effects on gastritis. The majority of the cells in the aggregates expressed the T cell marker CD3 or the B cell marker B220. Adoptive transfer of SAMP1/YitFcs CD4(+) T helper cells, with or without B cells, into immunodeficient recipients induced a pangastritis and duodenitis. SAMP1/YitFcs and AKR mice manifest hypochlorhydria and anti-parietal cell antibodies. These data suggest that common genetic factors controlling gastroenteric disease in SAMP1/YitFcs mice regulate distinct pathogenic mechanisms causing inflammation in separate sites within the digestive tract.

Coating Human Pancreatic Islets With CD4+CD25highCD127− Regulatory T Cells as a Novel Approach for the Local Immunoprotection

To develop a novel approach for local immunoprotection using CD4(+)CD25(high)CD127(-) T regulatory cells (Tregs) attached to the surface of the islets before transplantation. Tregs expanded ex vivo can control allo and autoreactivity, therefore, Treg-based therapy may offer more effective protection for transplanted islets from immunologic attack than currently used immunosuppression. Local application of Tregs can make such therapy more clinically feasible and efficient. Human islets were isolated and coated with allogeneic ex vivo expanded Tregs using biotin-poly(ethylene glycol)-N-hydroxysuccinimide ester (biotin-PEG-NHS) and streptavidin as binding molecules. Coating pancreatic islets with Tregs did not affect islet viability (>90% fluorescein diacetate/propidium iodide) or the insulin secretion profile in dynamic islet perifusion assays. After in vitro incubation with allogeneic T effector cells, Treg-coated islets revealed preserved function with higher insulin secretion compared with controls-native islets, coated islets with T effector cells or when Tregs were added to the culture, but not attached to islets (P < 0.05). In addition, the Enzyme-linked immunosorbent spot (ELISPOT) assay revealed suppression of interferon (IFN)-γ secretion, when T effector cells were challenged with Treg-coated islets comparing to controls (99 ± 7 vs 151 ± 8 dots, respectively; P < 0.01). We demonstrated, for the first time, the ability to bind immune regulatory cells to target cells with preservation of their viability and function and protective activity against immune attack. If successfully tested in an animal model, local delivery of immunoprotective Tregs on the surface of transplanted pancreatic islets may be an alternative or improvement to the currently used immunosuppression.

Limited immunogenicity of HIV CD8+ T-cell epitopes in acute Clade C virus infection.

Human immunodeficiency virus type 1 (HIV-1)-specific CD8(+) responses contribute to the decline in acute peak viremia following infection. However, data on the relative immunogenicity of CD8(+) T-cell epitopes during and after acute viremia are lacking. We characterized CD8(+) T-cell responses in 20 acutely infected, antiretroviral-naive individuals with HIV-1 subtype C infection using the interferon-γ enzyme-linked immunosorbent spot assay. Eleven of these had not fully seroconverted at the time of analysis. Viruses from plasma were sequenced within defined cytotoxic T-lymphocyte (CTL) cell epitopes for selected subjects. At approximately 28 days after estimated initial infection, CD8(+) T-cell responses were directed against an average of 3 of the 410 peptides tested (range, 0-6); 2 individuals had no detectable responses at this time. At 18 weeks, the average number of peptides targeted had increased to 5 (range 0-11). Of the 56 optimal Gag CTL epitopes sequenced, 31 were wild-type in the infecting viruses, but only 11 of 31 elicited measurable CD8(+) T-cell responses. These data demonstrate that the majority of CD8(+) responses are not elicited during acute HIV infection despite the presence of the cognate epitope in the infecting strain. There is a need to define factors that influence lack of induction of effective immune responses and the parameters that dictate immunodominance in acute infection.