EpiScreen™ – T cell epitope mapping
EpiScreen™ T cell epitope mapping assays identify CD4+ T cell epitopes within protein sequences in order to design deimmunised variants with a lower risk of immunogenicity in the clinic.
The highly sensitive ex vivo T cell assay can identify the precise location, number and magnitude of T cell epitopes in toxins, protein scaffolds and both human and non-human proteins. This information can be used to aid deimmunisation and contributes to the reduction in risk of clinical immunogenicity.
Accurate mapping of CD4+ T cell epitopes
In CD4+ T cell epitope mapping studies, 15mer peptides with a 12 amino acid overlap are synthesised spanning the test sample sequence. Individual peptides are then tested against CD8+ T cell-depleted PBMCs which contain APCs and CD4+ T cells at physiological ratios from 50 donors with >80% DRB1 allotypic coverage of the world population. Peptides may displace other peptides already bound to MHC class II or are taken up by antigen-presenting cells such as dendritic cells which process the peptides and present them in the form of linear peptides bound in the groove of MHC class II. Binding of the T cell receptor to these MHC class II/peptide complexes by CD4+ T cells can trigger an activation cascade causing T cell proliferation. T cell activation is determined by measuring T cell proliferation using 3H-thymidine uptake.
Significant immunogenicity is determined through predetermined statistical assessment of the dataset using the T-test to provide details on magnitude of T cell response based on stimulation index normalisation against background/vehicle control. T cell epitopes are then identified by comparing overlapping immunogenic peptides to identify the core T cell epitope sequence.
Below: PBMC from 50 healthy donors were used to map the location of T cell epitopes in variable regions of antibody variants A to C. Peptides containing T cell epitopes are identified by the frequency (%) response above the background threshold (red dotted line). Five CD4+ T cell epitopes were identified in variable regions of both antibodies A and B whilst none were found in the non-immunogenic antibody C.
Working with Abzena
Abzena’s discovery services are tailored for each project to ensure that the objectives are met or exceeded. Experienced project teams are assigned to each study focusing on progressing projects through to results in the minimum amount of time. Our clients widely regard us as professional and attentive partners who deliver quality results.
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