title: Regulated expression of human histocompatibility leukocyte antigen (HLA)-DO during antigen-dependent and antigen-independent phases of B cell development.
abstract: Human histocompatibility leukocyte antigen (HLA)-DO, a lysosomal resident major histocompatibility complex class II molecule expressed in B cells, has previously been shown to be a negative regulator of HLA-DM peptide loading function. We analyze the expression of DO in human peripheral blood, lymph node, tonsil, and bone marrow to determine if DO expression is modulated in the physiological setting. B cells, but not monocytes or monocyte-derived dendritic cells, are observed to express this protein. Preclearing experiments demonstrate that approximately 50% of HLA-DM is bound to DO in peripheral blood B cells. HLA-DM and HLA-DR expression is demonstrated early in B cell development, beginning at the pro-B stage in adult human bone marrow. In contrast, DO expression is initiated only after B cell development is complete. In all situations, there is a striking correlation between intracellular DO expression and cell surface class II-associated invariant chain peptide expression, which suggests that DO substantially inhibits DM function in primary human B cells. We report that the expression of DO is markedly downmodulated in human germinal center B cells. Modulation of DO expression may provide a mechanism to regulate peptide loading activity and antigen presentation by B cells during the development of humoral immune responses.
authors.affiliation: Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA.
authors.forename: Xinjian
authors.initials: X
authors.lastname: Chen
authors.forename: Oskar
authors.initials: O
authors.lastname: Laur
authors.forename: Taku
authors.initials: T
authors.lastname: Kambayashi
authors.forename: Shiyong
authors.initials: S
authors.lastname: Li
authors.forename: Robert A
authors.initials: RA
authors.lastname: Bray
authors.forename: Dominique A
authors.initials: DA
authors.lastname: Weber
authors.forename: Lars
authors.initials: L
authors.lastname: Karlsson
authors.forename: Peter E
authors.initials: PE
authors.lastname: Jensen
mesh_terms: D000328:Adult; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D001854:Bone Marrow Cells / Q000166:cytology / Q000276:immunology; D002454:Cell Differentiation; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology; D015536:Down-Regulation; D018858:Germinal Center / Q000276:immunology; D006681:HLA-D Antigens / Q000096:biosynthesis* / Q000276:immunology; D006801:Humans; D009000:Monocytes / Q000166:cytology / Q000276:immunology
chemical_list: D006681:HLA-D Antigens; C084245:HLA-DM antigens; C046148:HLA-DO antigens