antigen processing and presentation of peptide antigen via MHC class Ib biological_process The process in which an antigen-presenting cell expresses peptide antigen in association with an MHC class Ib protein complex on its cell surface. The peptide antigen may originate from an endogenous or exogenous protein. Class Ib here refers to non-classical class I molecules, such as those of the HLA-E family. peptide antigen processing and presentation via MHC class Ib GO:0002428 antigen processing and presentation via MHC class Ib antigen processing and presentation of peptide antigen