Analysis of HBV-Specific CD4 T-cell Responses and Identification of HLA-DR-Restricted CD4 T-Cell Epitopes Based on a Peptide Matrix
October 20th, 2021
Based on a hepatitis B virus (HBV)-derived peptide matrix, HBV-specific CD4 T-cell responses could be evaluated in parallel with identification of HBV-specific CD4 T-cell epitopes.
In a Chronic HBV infection, CD4 T cells play important roles in both viral clearance and the returners. This method enables us to evaluate HBV specific CD4 T cell responses and identify HBV specific CD4 T cell epitopes, simultaneously. Demonstrating the procedure will be Jianmei Xiao, a research assistant.
And Xing Wan, a technician from Bilao. To begin, isolate peripheral blood mononuclear cells, or PBMCs, from blood, using Ficoll density gradient centrifugation at 800 times G for 20 minutes. Then, collect the granulocytes between the and red blood cell layer, using a pasteur pipette.
Transfer the thawed cell suspension to a 15 milliliter centrifuge tube, Add one milliliter of the pre warmed Benzonase RPMI 1640, drop wise, then slowly add another six milliliters. Rinse the cryo vial with two milliliters of Benzonase RPMI 1640 to retrieve the remaining cells. Then centrifuge the tube at 400 times G for 10 minutes.
Remove the supernatant and loosen the pellet by tapping the tube. Gently re-suspend the pellet in one milliliter of warm Bensenase NACE RPMI 1640. Mix the cells gently, and filter them through a 70 micrometer cell strainer, if any cell clumps are visible.
Count viable cells using trypan blue and a hemocytometer. Re-suspend the PBMCs and complete culture medium, containing 10 units per milliliter IL2, and 10 nanograms per milliliter IL7. Adjust the cell density to 1.5x10 to the 6 cells per milliliter.
Then plate the cells in 96-Well flat bottom plates at a density of 3x10 to the fifth cells per well. Add hepatitis B virus or HBV derived peptide pools to each Well. For the background and positive control Wells, add the same amount of solvent.
Incubate the plates at 37 degrees Celsius and 5%carbon dioxide. On day three, supplement the culture medium with 50 units per milliliter of IL2, and 10 nanograms per milliliter of IL7. On day seven, replace half of the culture medium with fresh medium containing:four micrograms per milliliter peptides, 100 units per milliliter IL2, and 20 nanograms per milliliter IL7.
On day 10, gently pipette the cells in each Well seven to nine times to dis-aggregate cell clusters. Count the number Of viable cells and transfer 2x10 to the fifth cells into each Well of a 96-Well round bottom plate for HPV specific CD4 T cell response analysis. For the residual cells in the 96-Well flat bottom plate, adjust the volume of the culture medium to 100 microliters by discarding excessive medium.
Then, supplement the culture with 100 microliters of fresh, complete culture medium, containing:four micrograms per milliliter peptides, 100 units per milliliter IL2, ans 20 nanograms per milliliter IL7. Continue culturing the cells at 37 degrees Celsius and 5%carbon dioxide for epitope identification on day 12. Wash the cells in the 96-Well round bottom plate by adding 200 microliters of RPMI 1640, centrifuging the plate at 550 times G for three minutes, and discarding the supernatant.
Repeat the wash twice using complete culture medium for the last wash. For each well of cells stimulated with a specific peptide pool, add 200 microliters of complete culture medium supplemented with the same peptide pool. For the Background Control Well, add complete culture medium, supplemented with one microliter per milliliter of DMSO.
For the Positive Control Well, add complete culture medium supplemented with one microliter per milliliter DMSO, 150 nanograms per milliliter PMA, and one micromole per liter of ionomycin. Incubate the plate at 37 degrees Celsius in 5%carbon dioxide for six hours. After one hour of incubation, add 1.37 micrograms per milliliter monensin to the culture.
After the six hour incubation is complete, centrifuge the plate at 550 times G for three minutes. Remove the supernatant and wash the cells once with 200 microliters of DPPs, as previously demonstrated. Stain for surface markers CD3, CD4 and CD8, and a viability marker.
After suspending the cells with vibrator, then refrigerate the plate at four degrees Celsius for 30 minutes. After washing the plate once with 200 microliters of DPBS, fix and permeabilize the cells, stain for intracellular cytokines, TNF Alpha and Interferon-gamma, and refrigerate the plate at four degrees Celsius for 45 minutes. Wash the cells once again, and re-suspend them in 150 microliters of flow cytometry buffer.
Then, acquire the flow cytometry data using a flow cytometer. Maintain allergenic B-lymphoblastoid cell lines, or BLCLs, in a T-75 flask. On day 12 of the PBMC expansion, count the number of viable BLCLs, and transfer them to 15 milliliter centrifuge tubes.
Centrifuge the cells at 350 times G for 10 minutes and remove the supernatant. Re-suspend the cell pellet and complete culture medium. Then aliquot the BLCLs to a 96-Well round bottom plate at 4x10 to the fourth cells per well, and 80 microliters of complete culture medium.
Add 10 micrograms per milliliter of a single peptide, and set two background controls. Peptide pulsing with HLADR blocking, and DMSO pulsing. Incubate the plates at 37 degrees Celsius and 5%carbon dioxide, for two hours.
Add 100 micrograms per milliliter Mitomycin C and incubate the plate at 37 degrees Celsius and 5%carbon dioxide for one hour. Wash the plate three times with 200 microliters of RPMI 1640 to remove unpulsed peptide and Mitomycin C, then re-suspend the cells in 120 microliters of complete culture medium, using vibrator. On day 12 of the PBMC expansion, transfer the PBMCs to a 96-Well round bottom plate.
Centrifuge the cells in the plate, remove the supernatant, and wash them twice with 200 microliters of RPMI 1640, as previously demonstrated. Re-suspend the PBMCs in each well with 210 microliters of complete culture medium. For the PBMC Wells chosen for epitope identification, aliquot 70 microliters of the cell suspension and mix with peptide pulsed BLCLs in three Wells, including two background controls.
Incubate the plate at 37 degrees Celsius and 5%carbon dioxide for six hours. After one hour of incubation, add 1.37 micrograms per milliliter monensin to the culture and bring the final volume in each well to 200 microliters with complete culture medium. In this representative example, the TNF Alpha and Interferon-gamma secreting CD4 T cell responses for peptide pool Core11 are lower than two times the background values, hence, considered negative.
Meanwhile, the responses for peptide pool Core09 are higher than two times the background, and considered positive. The gray background indicates Wells with a positive CD4 T cell response and candidate peptides for epitope identification are indicated in red, Core01 has the highest response rate, judging from both TNF Alpha and Interferon-gamma secreting CD4T cells in column peptide pools. Peptides C1 to 15, C31 to 45, C61 to 75, and C91 to 105 in this peptide pool, are set as candidate peptides as the row of peptide pools containing those peptides also show positive results.
PBMCs expanded with peptide pools Core07, 08, 09 and 10, are used for epitope identification of these peptides. Similarly, Core09 has the highest response rate in row peptide pools. All the peptides in this pool are set as candidate peptides and PBMCs expanded with peptide pools:Core01, 02, 03, 04, 05 and 06 are used for epitope identification of these peptides.
For peptide pool Core08 expanded PBMCs, after stimulation with peptide C31 to 45 pulsed BLCLs, the frequencies of TNF Alpha and Interferon-gamma secreting CD4 T cells are two times higher than background controls. Thus, peptide C31 to 45 is a verified HLADR restricted CD4 T cell epitope. It was there, additional expanded PBMCs remaining after epitope identification.
Fine marking of the identified epitopes can be performed using a panel of shortened peptides.
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Overview
This article presents a detailed protocol for evaluating hepatitis B virus (HBV)-specific CD4 T cell responses and simultaneously identifying HBV-specific CD4 T cell epitopes using peripheral blood mononuclear cells (PBMCs) from patients with chronic HBV infection. The method combines peptide stimulation, cell culture, and flow cytometry to characterize functional CD4 T cell subsets and map their antigenic targets.
Key Study Components
Area of Science
- Immunology
- Virology
- Cellular biology
Background
- CD4 T cells are crucial in the immune response to chronic hepatitis B infection, influencing both viral clearance and disease progression.
- CD4 T cells can be classified into functional subsets based on cytokine secretion, such as Th1 (IFN-γ), Th2 (IL-4, IL-13), Tfh (IL-21), and Th17 (IL-17).
- Understanding the specificity and function of HBV-specific CD4 T cells is important for elucidating immune mechanisms in chronic HBV infection.
- Current limitations include restricted knowledge of HBV-specific CD4 T cell epitopes and challenges in isolating viable antigen-specific cells.
Purpose of Study
- To develop and demonstrate a method for evaluating HBV-specific CD4 T cell responses in chronic HBV patients.
- To identify HBV-specific CD4 T cell epitopes using a peptide matrix approach.
- To characterize the functional subsets of HBV-specific CD4 T cells based on cytokine secretion profiles.
Methods Used
- Isolation of PBMCs from blood using Ficoll density gradient centrifugation.
- Expansion and stimulation of PBMCs with HBV-derived peptide pools in culture with IL-2 and IL-7.
- Sequential culture steps with periodic medium supplementation and peptide restimulation.
- Flow cytometry analysis of CD4 T cell responses, including surface and intracellular cytokine staining (TNF-α, IFN-γ).
- Epitope identification using peptide-pulsed B-lymphoblastoid cell lines (BLCLs) and co-culture with expanded PBMCs.
Main Results
- The protocol enables detection of HBV-specific CD4 T cell responses by measuring cytokine secretion after peptide stimulation.
- Positive responses are defined as cytokine-secreting CD4 T cells exceeding twice the background control.
- The method allows mapping of candidate and verified CD4 T cell epitopes within HBV peptide pools.
- Fine mapping of epitopes can be performed using panels of shortened peptides.
Conclusions
- This approach provides a robust platform for simultaneous evaluation of HBV-specific CD4 T cell responses and epitope identification.
- The method facilitates functional characterization of CD4 T cell subsets in chronic HBV infection.
- It can be adapted for further detailed studies of antigen-specific T cell responses in viral infections.
Frequently Asked Questions
Executive Industry Relevance
Robust identification and functional profiling of HBV-specific CD4 T cell epitopes are critical for de-risking immunological targets and advancing antiviral discovery portfolios. This peptide matrix-based workflow enables simultaneous quantification of antigen-specific responses and epitope mapping, supporting predictive confidence in early-stage immunology programs. The approach strengthens translational continuity by providing actionable data for target validation and mechanistic de-risking in chronic hepatitis B research.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Enables direct interrogation of HBV-specific CD4 T cell responses for functional target validation.
- Supports mechanistic de-risking by mapping HLA-DR-restricted epitopes relevant to immune modulation.
- Facilitates portfolio triage by distinguishing immunodominant versus subdominant T cell targets.
Screening & Assay Development
- Prepares validated PBMC-based systems for downstream immunological screening workflows.
- Delivers reproducible, quantitative cytokine readouts for assay standardization and benchmarking.
- Enables scalable screening of peptide libraries for epitope discovery and immune profiling.
Translational & Preclinical Research
- Aligns functional T cell data with disease-relevant immune signatures in chronic HBV infection.
- Supports continuity from discovery through preclinical validation by enabling fine epitope mapping.
- Provides a foundation for translational biomarker development in antiviral and immunotherapy pipelines.
Pipeline & Workflow Integration
This method integrates into the immunology discovery continuum, spanning early target validation, lead identification, and translational research for chronic viral diseases.
- Discovery Biology: Supports hypothesis testing and pathway clarification by quantifying antigen-specific CD4 T cell responses.
- Screening: Provides assay-ready, reproducible PBMC systems with quantitative cytokine outputs for immune screening.
- Analytics: Delivers flow cytometry-based measurements and statistical thresholds for response positivity.
- Translational Research: Enables mapping of disease-relevant epitopes for biomarker and therapeutic target alignment.
- Enterprise Reuse: Offers a reusable platform for epitope discovery across diverse viral and immunological targets.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence and reduces mechanistic ambiguity in immune target validation.
- Operational Value: Standardizes PBMC-based assays for reproducibility and scalability in immunology workflows.
- Strategic Value: Informs go/no-go decisions and enhances capital efficiency by focusing on validated immune targets.
- Portfolio Impact: Supports risk-adjusted prioritization and advancement of immunomodulatory candidates.
Implementation Considerations
- Requires expertise in PBMC isolation, peptide stimulation, and flow cytometry analysis.
- Demands access to high-quality analytical instrumentation and cell culture infrastructure.
- Necessitates cross-team standardization of cytokine measurement and response thresholds.
- Adaptation may be needed for different HLA backgrounds or viral antigens.
- Dependent on availability of well-characterized peptide libraries and validated controls.
Biopharma FAQs
Chapters in this video
0:04
Introduction
0:51
Isolation of PBMCs and In Vitro Expansion Using an HBV Peptide Matrix
3:55
Analysis of HBV-specific CD4 T-Cell Responses by Intracellular Flow Cytometry
5:54
Identification of HBV-specific HLA-DR Restricted CD4 T-Cell Epitopes
8:07
Results: Identification of HBV-specific HLA-DR Restricted CD4 T-Cell Epitopes
10:06
Conclusion
