Human leukocyte antigen class II molecule (HLA class II)

Human leukocyte antigen class II molecules are heterodimeric transmembrane glycoproteins primarily expressed on professional antigen-presenting cells (such as B cells, dendritic cells, and macrophages)[1][2][4][5]. They consist of an α and β chain encoded by the HLA-DR, -DP, and -DQ loci, and their chief role is to bind and present extracellularly derived peptides to CD4+ helper T lymphocytes, thereby initiating and regulating immune responses[2][5][7][8]. The peptide-binding groove of HLA class II is open-ended, allowing presentation of longer peptides compared to class I molecules[1][4]. Extensive genetic diversity in HLA class II influences susceptibility to many infectious and autoimmune diseases, affects antibody repertoire, and serves as a critical barrier and predictive marker in organ transplantation[3][6][8][9]. HLA class II proteins are among the most clinically significant immunological targets due to their central role in adaptive immunity, their impact on disease susceptibility, and their implications in immunotherapy and patient stratification[5][9].

Other names

HLA class IIMHC class IIMajor histocompatibility complex class IIHLA-DRHLA-DPHLA-DQ

Inhibition of antigen presentation to CD4+ T cells Modulation of T cell co-stimulation Suppression of T cell activation