HLA-B is a major histocompatibility complex class I molecule that presents peptide antigens to CD8+ T cells, initiating adaptive immunity against infections and cancers 1. The protein displays peptides with characteristic motifs, such as proline at position 2 and leucine anchor residues at the C-terminus, depending on the allelic variant 2. HLA-B functions through multiple antigen-processing pathways, including TAP-dependent and TAP-independent mechanisms in the endoplasmic reticulum, and can acquire exogenous antigens in certain cell types like monocytes 2. Surface expression levels and peptide-binding stability vary significantly across HLA-B allotypes and cell types, influencing immune responsiveness 2. Clinically, HLA-B polymorphisms associate with multiple diseases: HLA-B*1502 shows strong association with carbamazepine-induced Stevens-Johnson syndrome in Han Chinese populations, enabling predictive testing 3. HLA-B*46 represents a risk factor for Graves' disease in Asian populations, with a 2.48-fold increased risk 4. These associations highlight HLA-B's critical role in both protective immunity and drug-induced immunopathology, making allele-specific testing clinically relevant for personalized medicine.