Dendritic Cell AssaysHLA Class II BindingMAPPs ImmunopeptidomicsT-Cell Functional Testing
Creative Peptides provides integrated in vitro immunogenicity risk assessment services for peptide, protein, conjugate, and other biologic research programs. Our platform examines key stages of the immune recognition pathway, including antigen uptake, dendritic cell activation, HLA class II binding, natural peptide presentation, and antigen-specific T-cell responses. By combining cell-based testing with MHC binding peptide screening, immunopeptidomics, and functional assays, we help research teams compare candidates, investigate sequence-related risks, and prioritize follow-up work without relying on a single predictive endpoint.
Immunogenicity risk cannot be inferred reliably from sequence prediction or one cell-based assay alone. A candidate may contain peptides that bind selected HLA alleles but are not generated during cellular processing. Conversely, an intact molecule may be efficiently taken up by antigen-presenting cells and generate naturally presented peptides that were not prioritized by an in silico screen.
A project-specific in vitro strategy can address practical questions such as:
Services can be used individually or combined in a staged testing strategy. Study design is aligned with the test article, development question, available material, expected mechanism, and required level of mechanistic resolution. Where peptide panels are needed, our custom peptide synthesis capabilities can support overlapping libraries, sequence variants, modification controls, and candidate epitope confirmation.
The dendritic cell uptake and activation assay evaluates how an intact test article interacts with human antigen-presenting cells before adaptive immune recognition. Donor-derived monocytes can be differentiated into dendritic cells and exposed to the candidate under project-defined conditions.
Deliverables may include donor-level flow cytometry data, concentration-response plots, activation marker summaries, cytokine results, control performance, and interpretation of uptake or activation differences.
HLA class II peptide binding assays measure the ability of defined peptides to bind selected HLA-DR, HLA-DP, or HLA-DQ molecules. The assay is useful for confirming predicted binders, ranking sequence regions, and comparing original and engineered variants.
HLA binding establishes molecular compatibility with selected alleles but does not demonstrate that a peptide is naturally processed or recognized by T cells. Results can therefore be integrated with MAPPs and T-cell epitope identification workflows.
The MHC-associated peptide proteomics assay evaluates which test article-derived peptides are naturally processed and presented by donor-derived antigen-presenting cells. It connects intact-molecule uptake and intracellular processing with HLA class II peptide presentation.
Deliverables can include identified peptide sequences, source-protein positions, donor and HLA context, detection patterns, sequence-region visualization, and cross-assay comparison. MAPPs is generally most informative for intact molecules that require cellular uptake and processing; short peptides may be better evaluated through direct HLA binding and functional T-cell testing.
T-cell activation and proliferation assays provide a functional assessment of whether a test article or candidate peptide can stimulate donor-derived T cells under the selected assay conditions. Assays can use PBMCs or enriched T-cell populations with appropriate antigen-presenting cells.
Functional results help confirm whether HLA-binding or naturally presented peptides are associated with measurable T-cell responses. Related antigen-specific cell characterization may be supported through tetramer-based T-cell detection when suitable peptide–HLA reagents are available.
Orthogonal assays are most useful when their results are interpreted against a clearly defined biological question. We integrate candidate attributes, donor information, assay controls, peptide-level findings, and functional data to develop a transparent relative-risk assessment.
The final report states assay limitations and avoids treating negative in vitro results as proof that an immune response cannot occur.
The appropriate assay depends on the biological step that needs to be investigated. The following table compares the central question, suitable test materials, primary outputs, and limitations of each service module.
| Assay Module | Primary Question | Suitable Test Material | Representative Readouts | Interpretive Limitation |
|---|---|---|---|---|
| Dendritic Cell Uptake | Is the intact candidate internalized by human antigen-presenting cells? | Proteins, conjugates, particles, labeled peptides, formulations, stressed samples | Uptake-positive cells, fluorescence intensity, uptake kinetics, viability | Label selection and labeling position may alter molecular behavior |
| Dendritic Cell Activation | Does the test article induce maturation or innate activation signals? | Intact candidates, formulations, aggregates, process-related comparison samples | CD80, CD83, CD86, HLA-DR, cytokines, cell viability | Activation may reflect formulation, impurity, aggregate, or cytotoxicity effects rather than sequence-specific recognition |
| HLA Class II Binding | Can a defined peptide bind selected HLA class II molecules? | Individual peptides, overlapping libraries, variants, junction peptides | Relative binding, competition data, binding concentration, allele-specific ranking | Binding does not establish natural processing or T-cell recognition |
| MAPPs Proteomics | Which candidate-derived peptides are naturally processed and presented? | Intact proteins, polypeptides, conjugates, and sufficiently processable constructs | HLA-associated peptide identity, source position, donor distribution, presentation clusters | Peptide detection is influenced by abundance, donor biology, sample preparation, and mass spectrometric sensitivity |
| T-Cell Activation | Does the candidate induce a functional donor T-cell response? | Intact candidates, peptide pools, confirmed epitopes, sequence variants | Activation markers, cytokine secretion, responding donor frequency | Low precursor frequency and donor variability can limit response detection |
| T-Cell Proliferation | Does antigen exposure drive expansion of responsive T cells? | Intact candidates, peptides, peptide pools, comparative constructs | Proliferating cell percentage, division profile, stimulation relative to controls | Culture duration and background proliferation require carefully matched controls |
| Integrated Panel | Which candidates or sequence regions show convergent evidence across the immune pathway? | Candidate series, engineered variants, modified molecules, reference materials | Cross-assay hotspot map, donor-level comparison, relative-risk ranking | Integrated in vitro evidence supports prioritization but does not provide an absolute prediction |
Reliable immunogenicity testing requires more than selecting an assay name. Donor composition, HLA representation, test article quality, concentration range, controls, and sample handling can materially affect the interpretation of results.
| Design Element | Decision Required | Potential Project Risk | Recommended Approach | Reported Information |
|---|---|---|---|---|
| Donor Panel | Number and diversity of donors appropriate for the project question | A small or poorly characterized panel may miss donor-dependent responses | Select donors according to assay purpose, available cells, HLA needs, and expected response frequency | Donor-level data rather than pooled results alone |
| HLA Characterization | Whether specific HLA-DR, HLA-DP, or HLA-DQ alleles must be represented | Relevant peptide–HLA interactions may be obscured without appropriate allele context | Align HLA selection with prediction results, binding data, MAPPs design, or donor availability | Applicable donor or recombinant HLA information |
| Test Article Quality | Identity, concentration, aggregation state, purity profile, and formulation suitability | Aggregates, impurities, precipitation, or concentration errors may produce misleading activation or exposure data | Review analytical information and confirm compatibility with assay media before testing | Material observations, preparation records, and deviations affecting interpretation |
| Peptide Preparation | Peptide length, overlap, solvent, concentration, pooling, and storage conditions | Hydrophobic peptides may precipitate, adsorb to plastic, oxidize, or be underrepresented in pools | Use sequence-aware solubilization, controlled pooling, and individual follow-up for problematic peptides | Peptide map, preparation conditions, and assay-ready concentrations |
| Concentration Range | Exposure levels that support interpretation without excessive cytotoxicity or nonspecific stimulation | A single concentration may miss weak responses or create high-dose artifacts | Use a project-appropriate concentration series with viability and vehicle monitoring | Concentration-response data and usable exposure range |
| Assay Controls | Positive, negative, vehicle, matrix, and reference controls needed for each module | Unmatched controls make it difficult to separate antigen-specific signals from background effects | Select controls according to assay mechanism, donor cells, test article format, and detection method | Control acceptance, background values, and normalization approach |
| Variant Comparison | Whether variants are tested as intact molecules, peptides, or both | Peptide-only testing may miss changes in uptake or processing, while intact-molecule testing may not localize the responsible sequence | Combine intact and peptide-level comparisons when both processing and sequence localization matter | Variant-specific assay results and mapped sequence differences |
| Data Thresholds | Criteria for calling a response, presentation event, or meaningful difference | Post hoc thresholds can overstate weak or variable findings | Define assay-specific acceptance and interpretation criteria during study planning | Raw data, calculated endpoints, criteria, and flagged borderline results |
Immune-Pathway Coverage
Study modules address uptake, dendritic cell activation, HLA binding, antigen processing, peptide presentation, and functional T-cell responses.
Donor-Aware Design
Donor selection, HLA context, biological variability, and donor-level reporting are incorporated into the study plan.
Peptide-Level Resolution
HLA-binding, MAPPs, and functional data can be mapped to specific sequence regions, junctions, modifications, or engineered variants.
Assay-Matched Controls
Controls are selected around each assay mechanism to identify background activation, vehicle effects, cytotoxicity, and nonspecific responses.
Integrated Interpretation
Results are evaluated across assays instead of treating HLA binding, peptide presentation, or T-cell activation as isolated evidence.
Flexible Sample Formats
Workflows can be adapted for peptides, proteins, fusion constructs, conjugates, modified candidates, formulations, and comparative samples.
The workflow is structured to answer a defined development question, preserve sample integrity, generate interpretable donor-level data, and connect results to practical next steps.
1
Candidate Review & Risk Question
2
Assay & Donor Planning
3
Sample Qualification & Testing
4
Data Review & Sequence Mapping
5
Reporting & Follow-Up Strategy
Integrated immunogenicity testing can support candidate selection and mechanistic investigation at multiple stages of peptide and protein research. Assay combinations are selected according to the molecular format and the decision that must be made.
Creative Peptides can develop a focused assay strategy for dendritic cell uptake and activation, HLA class II peptide binding, MAPPs proteomics, T-cell activation, and T-cell proliferation. To discuss the most appropriate test sequence, please provide the candidate format, sequence or construct information, formulation, available sample quantity, comparison groups, and the decision your team needs to make. Contact us to request a project review and customized study plan.
It examines selected steps that may contribute to an immune response, including antigen uptake, dendritic cell activation, HLA class II binding, natural peptide presentation, and functional T-cell responses.
No. Each assay addresses a different biological step. Combining complementary assays provides stronger relative-risk information than relying on a single endpoint.
HLA binding tests whether a defined peptide can bind a selected HLA molecule. MAPPs identifies peptides that are generated from an intact test article and naturally presented by antigen-presenting cells.
MAPPs is most informative for intact proteins, polypeptides, conjugates, or other constructs that undergo cellular uptake and antigen processing. Very short peptides may be better assessed by direct HLA-binding and T-cell assays.
Donors differ in HLA genotype, immune history, and antigen-specific T-cell repertoire. Testing multiple donors helps reveal donor-dependent responses and prevents conclusions from relying on one biological background.
