Mouse H-2 Complex is the murine equivalent of the human Major Histocompatibility Complex (MHC), located on chromosome 17. It encodes molecules essential for antigen presentation and immune regulation and is divided into: Class I – expressed on all nucleated cells from mice of the a, b, d, j, k, s, and u haplotypes; presents endogenous peptides to CD8⁺ T cells via the CD3/TCR complex, aiding cytotoxic immune responses; Class II – expressed mainly on antigen-presenting cells; presents exogenous peptides to CD4⁺ T cells; Class III – encodes immune-related proteins such as complement components and cytokines.