Technical Articles

The MHC IIb molecule belongs to the non classical MHC class II subtype, and its gene localization, protein structure, and antigen presentation mechanism differ significantly from the classical MHC IIa molecule. These types of molecules (such as H2-O and H2-M in mice and HLA-DM and HLA-DO in humans) do not directly participate in the exogenous presentation of antigen peptides, but indirectly affect the activation and immune response intensity of CD4 ⁺ T cells by regulating the peptide loading, editing, and exchange processes of classical MHC-II molecules.

MHC IIa molecules are a classic subtype of the major histocompatibility complex class II, primarily expressed on the surface of specialized antigen-presenting cells such as dendritic cells and B cells. Unlike MHC-I, which is primarily responsible for endogenous antigen presentation, MHC-IIa specifically presents exogenous antigen peptides to CD4 ⁺ T helper cells to initiate and regulate adaptive immune responses.