EpiScreen® 2.0 MAPPs: MHC Class II Associated Peptide Proteomics

CD14 positive mononuclear cells are purified from PBMC and differentiated into immature DCs, loaded with test proteins and then matured. The DCs take up and process the proteins, presenting them as linear peptides bound in the groove of MHC class II. The DCs are lysed and MHC class II bound peptide complexes are captured by immunoprecipitation using a pan-HLA-DR antibody. Naturally processed and presented peptides, from the test sample, are eluted from the captured MHC molecules for subsequent analysis by nano-LC-MS/MS.

Eluted peptides are identified using a common search algorithm and an in-house database. Identified peptides typically occur as different length variants. These variants share the same core HLA-DR binding motif and effectively form a cluster. Eluted peptides are analysed using iTope-AI and interrogated against the TCED™ database to identify possible epitopes.

Peptides presented from the test sample can be run through an EpiScreen® 2.0 T Cell Epitope Mapping Assay to identify those epitopes that bind T cell receptors and trigger an activation cascade causing T cell proliferation.