The clone IVA12 recognizes the shared epitopes of human leukocyte antigen (HLA) class II molecules HLA-DP, HLA-DQ and HLA-DR heterodimeric cell surface glycoproteins comprised of an α (heavy) chain and a β (light) chain. They are expressed on B cells, activated T cells, monocytes/macrophages, dendritic cells, and other non-professional antigen presenting cells (APCs). HLA-Class II expressing APCs specifically present antigens recognized by TCR/CD3 complex of CD4+ T cells. Reactive microglia and perivascular cells in multiple sclerosis lesions express all three types of HLA-Class II molecules, whereas microglia in the normal CNS express HLA-DR only.
