PIRB Recombinant Rabbit mAb (S-6517)

PIRB (Paired immunoglobulin-like receptor B) is an important inhibitory immune receptor in mice, belonging to the immunoglobulin superfamily. Its gene is located on mouse chromosome 7, and it is mainly expressed on B cells, myeloid cells, and subsets of neurons in the central nervous system. The intracellular portion of this receptor contains four immunoreceptor tyrosine-based inhibitory motifs (ITIMs); upon ligand binding, the ITIMs undergo tyrosine phosphorylation and recruit SHP-1 and SHP-2 phosphatases, thereby transducing inhibitory signals. In the immune system, PIRB participates in regulating B cell homeostasis, myeloid dendritic cell differentiation, and inflammatory responses—for example, it negatively regulates T cell-dependent intestinal inflammation. Notably, PIRB also plays key functions in the nervous system: it is expressed on cortical neurons as a receptor for MHC class I molecules and is associated with synapses, restricting ocular dominance plasticity in the adult visual cortex and thereby stabilizing neural circuits. In addition, PIRB has been identified as the entry receptor for mammalian orthoreovirus. It should be noted that PIRB is not a strict one-to-one ortholog of human LILRB3; it overlaps with several human LILR members (especially LILRB2) in ligand recognition and function, so species differences should be considered when extrapolating findings from mouse PIRB to human immunology.