EpiScreen® 2.0 MAPPs: MHC Class II Associated Peptide Proteomics

In the MAPPs assay, CD14-positive mononuclear cells are purified from PBMCs and differentiated into immature dendritic cells (DCs). These DCs are loaded with test proteins, matured, and then process the proteins into linear peptides presented in MHC Class II grooves. The DCs are lysed, and MHC Class II–bound peptide complexes are captured by immunoprecipitation using a pan-HLA-DR antibody. Naturally processed peptides are eluted from the captured complexes for analysis by nano-LC-MS/MS.

Eluted peptides are identified using a standardized search algorithm and Abzena’s in-house database. These peptides typically appear in length variants sharing the same core HLA-DR binding motif. Data are analyzed using iTope-AI and the TCED™ database, enabling immunogenicity assay development to identify potential T-cell epitopes.

Peptides detected through the MAPPs assay can be evaluated further in in vitro immunogenicity assays, such as the EpiScreen® 2.0 T-cell Epitope Mapping Assay, to confirm T-cell binding and activation that drive immune proliferation.