FITC Mouse Anti-Human HLA-B27 Antibody (S-4040)

HLA-B27 is a highly polymorphic class I major histocompatibility complex (MHC-I) molecule expressed on virtually all nucleated cells that folds in the endoplasmic reticulum with β2-microglobulin to form a peptide-binding groove preferentially anchoring arginine at position 2, transports these peptides to the cell surface for surveillance by CD8⁺ cytotoxic T lymphocytes, and—through mechanisms still debated encompassing presentation of “arthritogenic” self or microbial peptides, heavy-chain misfolding that triggers endoplasmic-reticulum stress and autophagy, and aberrant homodimer formation that activates innate killer receptors—confers the strongest known genetic risk for the spondyloarthritis family (ankylosing spondylitis, reactive arthritis, psoriatic arthritis, juvenile enthesitis-related arthritis) and acute anterior uveitis while paradoxically protecting against several viral infections, with disease-associated subtypes such as B27:05 and B27:04 differing from non-associated or protective subtypes by only one or two amino acids lining the antigen-binding cleft that alter peptide repertoire and surface stability.