Mouse Major Histocompatibility Complex class II I-Ad (I-Ad)

Mouse MHC class II I-Ad is a heterodimeric cell surface glycoprotein expressed primarily on professional antigen-presenting cells such as dendritic cells, B cells, and macrophages in mice of the d haplotype, such as the BALB/c strain (Janeway's Immunobiology, 9th Ed.). It is composed of an alpha chain (H2-Aa) and a beta chain (H2-Ab1) that non-covalently associate to form a peptide-binding groove (UniProt P04228, P06340). The primary biological function of I-Ad is to bind exogenous peptides derived from endocytosed proteins and present them to the T-cell receptor (TCR) of CD4+ helper T cells, thereby initiating and regulating the adaptive immune response (Murphy & Weaver, 2016). In biomedical research, I-Ad is a critical target for studying autoimmune diseases, such as type 1 diabetes and experimental autoimmune encephalomyelitis, where specific self-peptides presented by I-Ad trigger pathogenic T cell responses (Unanue, 2011). Therapeutic strategies targeting I-Ad include the use of altered peptide ligands or monoclonal antibodies to block antigen presentation or induce immune tolerance (Fairchild et al., 1993). While I-Ad is a mouse-specific molecule, it serves as a vital surrogate for understanding human HLA class II functions and developing immunotherapies for human conditions (NCBI Gene).

Other names

H2-AdH-2 class II I-AdI-A(d)Mouse MHC II I-AdH2-IA-dH2-Aa/H2-Ab1

Competitive inhibition of peptide binding to the MHC class II groove or direct blockade of the MHC-TCR interaction to modulate CD4+ T cell activation.