MERS-CoV‒Specific T-Cell Responses in Camels after Single MVA-MERS-S Vaccination

We developed an ELISPOT assay for evaluating Middle East respiratory syndrome coronavirus (MERS-CoV)‒specific T-cell responses in dromedary camels. After single modified vaccinia virus Ankara-MERS-S vaccination, seropositive camels showed increased levels of MERS-CoV‒specific T cells and antibodies, indicating suitability of camel vaccinations in disease-endemic areas as a promising approach to control infection.

T Cell Responses to Dystrophin in a Natural History Study of Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is caused by the lack of dystrophin, but many patients have rare revertant fibers that express dystrophin. The skeletal muscle pathology of DMD patients includes immune cell infiltration and inflammatory cascades. There are several strategies to restore dystrophin in skeletal muscles of patients, including exon skipping and gene therapy. There is some evidence that dystrophin restoration leads to a reduction in immune cells, but dystrophin epitopes expressed in revertant fibers or following genome editing, cell therapy, or microdystrophin delivery after adeno-associated viral gene therapy may elicit T cell production in patients. This may affect the efficacy of the therapeutic intervention, and potentially lead to serious adverse events. To confirm and extend previous studies, we performed annual enzyme- linked immunospot interferon-gamma assays on peripheral blood mononuclear cells from 77 pediatric boys with DMD recruited into a natural history study, 69 of whom (89.6%) were treated with corticosteroids. T cell responses to dystrophin were quantified using a total of 368 peptides spanning the entire dystrophin protein, organized into nine peptide pools. Peptide mapping pools were used to further localize the immune response in one positive patient. Six (7.8%) patients had a T cell-mediated immune response to dystrophin at at least one time point. All patients who had a positive result had been treated with corticosteroids, either prednisolone or prednisone. Our results show that ∼8% of DMD individuals in our cohort have a pre-existing T cell-mediated immune response to dystrophin, despite steroid treatment. Although these responses are relatively low level, this information should be considered a useful immunological baseline before undertaking clinical trials and future DMD studies. We further highlight the importance for a robust, reproducible standard operating procedure for collecting, storing, and shipping samples from multiple centers to minimize the number of inconclusive data.

Alternative Evaluation of an ELISPOT Assay Using Cytokine Activity as a Novel Parameter

BACKGROUND/AIM

The enzyme-linked immunospot (ELISPOT) assay is a well-established method used to evaluate the strength of T cell-mediated immune activity, and accepted as a standard functional immunological assay. Cytokine activity is a novel parameter reflecting spot size and intensity, which has not been used in ELISPOT assay before.

MATERIALS AND METHODS

In the present study, from 113 ELISPOT assay data derived from previous clinical trials with dendritic cell vaccines, both spot number count and cytokine activity data for IFN-γ secretion were obtained using an ELISPOT reader. Comparing the new parameter cytokine activity with the existing parameter spot number, the feasibility of cytokine activity was investigated.

RESULTS

There were no significant differences in sensitivity and specificity between spot number and cytokine activity among ELISPOT assay data from CMVpp65 and other antigen peptide-stimulated cytotoxic T lymphocytes.

CONCLUSION

Although cytokine activity is a novel parameter unreported so far, it did not show any advantages in the evaluation T cell immune responses compared to the existing spot number parameter.

The Ability of a Cytomegalovirus ELISPOT Assay to Predict Outcome of Low-Level CMV Reactivation in Hematopoietic Cell Transplant Recipients

BACKGROUND

Cytomegalovirus (CMV) infections in hematopoietic cell transplant (HCT) recipients cause substantial morbidity and mortality. CMV cell-mediated immunity (CMV-CMI) can be determined by levels of interferon gamma (IFN-γ) production using an enzyme-linked immunospot (ELISPOT) CMV assay (T-SPOT.CMV assay). In this study, we evaluated the ability of this assay to predict the outcome of low-level CMV reactivation in HCT recipients.

METHODS

We followed 55 HCT recipients with low-level CMV reactivation up to 8 weeks from enrollment. Progression to clinically significant CMV infection (CS-CMVi) was defined as a CMV load >1000 IU/mL or > 500 IU/mL in patients receiving matched related/autologous or matched unrelated transplants, respectively, and initiation of antiviral treatment.

RESULTS

Progression to CS-CMVi occurred in 31 (56%) of the HCT recipients. Spot counts of CMV-specific pp65 and IE1 antigens were significantly lower in patients who had CS-CMVi than in patients who did not. On multivariate analysis, the ELISPOT CMV responses and steroids use were the only predictors of progression to CS-CMVi.

CONCLUSIONS

A strong association between low CMV-CMI and progression to CS-CMVi was observed in HCT recipients. The implementation of serial monitoring of CMV-CMI may identify patients at risk of progression to CS-CMVi that require antiviral therapy.

Luminex-Coupled EliFACS: A Multiparametric Method to Enumerate and Functionally Characterize Antigen-Specific T cells in Human Peripheral Blood

We describe a Luminex-coupled EliFACS assay that integrates multiplexing technology, enzyme-linked immunospot (ELISPOT), and intracellular cytokine FACS staining for the detection of multiple parameters of antigen-specific T-cell activation in human peripheral blood. Although our protocol is for measuring T-cell responses against cardiac myosin heavy chain and myelin basic protein, the major autoantigens in myocarditis and multiple sclerosis, respectively, these methods could be used for the detection of T-cell responses to other antigens, including foreign antigens.

Generation and Analysis of Humanized Mouse Model of EBV Infection

The recent development of severely immunodeficient mouse strains enabled the production of new-generation humanized mice, in which major components of the human immune system are reconstituted. These new-generation humanized mice can be infected with human pathogenic viruses that do not infect regular mice and target cells of the hematoimmune system. Here we describe the method for preparing humanized mice, infecting them with EBV, and for their virological and immunological analyses. The results obtained from our own mouse models are briefly described.

Fungal peptides from pneumonitis hypersensitivity etiologic agents are able to induce specific cellular immune response

PURPOSE

Hypersensitivity pneumonitis (HP) is an immunoallergic disease due to chronic exposure to high quantities of different microorganisms such as Mycobacterium immunogenum (Mi), a mycobacterium, and Lichtheimia corymbifera (Lc), a filamentous fungus. It has recently been demonstrated that the protein DLDH (dihydrolipoyl dehydrogenase), is common to these microorganisms. This study aimed to investigate the immune potential of overlapping peptide pools covering the MiDLDH and LcDLDH.

EXPERIMENTAL DESIGN

A selection of 34 peptides, from the MiDLDH and LcDLDH, able to interact with Major Histocompatibility Complex (MHC) 1 and MHC 2, was obtained using three different epitope prediction websites. By means of ELISPOT assays, we compared the frequency of Interferon gamma (IFNγ) secreting peripheral blood mononuclear cells (PBMC) after stimulation with overlapping peptide pools. Tests were performed using cells from 35 healthy blood donors.

RESULTS

One peptide pool containing five peptides from MiDLDH and able to interact with MHC 2 induced a marked IFNγ specific immune response (Pool F, p<0.001, Wilcoxon signed-rank test).

CONCLUSION

This study demonstrated that peptides from microorganisms involved in HP were able to induce a high IFNγ specific immune response after stimulation of PBMCs from healthy blood donors which could be useful to develop an effective prevention strategy.

Dendritic cells pulsed with hsp70-peptide complexes derived from human hepatocellular carcinoma induce specific anti-tumor immune responses

AIM: To investigate the anti-tumor effect of dendritic cells (DCs) pulsed with hsp70-peptide complexes derived from human hepatocellular carcinoma (HCC) cells on human T cells.

METHODS: Hsp70-peptide complexes were purified from human HCC cells with column chromatography using ADP-agarose and DEAE-Sepharose. DCs were derived from peripheral blood mononuclear cells of healthy donors in the presence of human GM-CSF and IL-4. The anti-tumor effect of DCs pulsed with hsp70-peptide complexes on human T-cell was assayed by CTL and enzyme-linked immunospot (ELISPOT) tests.

RESULTS: Hsp70-peptide complexes derived from human HCC cells activated phenotypic and functional maturation of DCs. The matured DCs stimulated a high level of autologous T-cell proliferation and type I cytokine secretion, and induced HCC-specific cytotoxic T lymphocytes (CTLs), which specifically killed HCC cells by a MHC class I restricted mechanism.

CONCLUSION: Hsp70-peptide complexes derived from human HCC cells can serve as a potent tumor antigen source for pulsing DCs, the pulsed DCs are very effective in activating specific T-cell responses against HCC cells.