title: Expression patterns of H2-O in mouse B cells and dendritic cells correlate with cell function.
abstract: In the endosomes of APCs, the MHC class II-like molecule H2-M catalyzes the exchange of class II-associated invariant chain peptides (CLIP) for antigenic peptides. H2-O is another class II-like molecule that modulates the peptide exchange activity of H2-M. Although the expression pattern of H2-O in mice has not been fully evaluated, H2-O is expressed by thymic epithelial cells, B cells, and dendritic cells (DCs). In this study, we investigated H2-O, H2-M, and I-A(b)-CLIP expression patterns in B cell subsets during B cell development and activation. H2-O was first detected in the transitional 1 B cell subset and high levels were maintained in marginal zone and follicular B cells. H2-O levels were down-regulated specifically in germinal center B cells. Unexpectedly, we found that mouse B cells may have a pool of H2-O that is not associated with H2-M. Additionally, we further evaluate H2-O and H2-M interactions in mouse DCs, as well as H2-O expression in bone marrow-derived DCs. We also evaluated H2-O, H2-M, I-A(b), and I-A(b)-CLIP expression in splenic DC subsets, in which H2-O expression levels varied among the splenic DC subsets. Although it has previously been shown that H2-O modifies the peptide repertoire, H2-O expression did not alter DC presentation of a number of endogenous and exogenous Ags. Our further characterization of H2-O expression in DCs, as well as the identification of a potential free pool of H2-O in mouse splenic B cells, suggest that H2-O may have a yet to be elucidated role in immune responses.
authors.affiliation: Cell Biology and Genetics Program, Weill Graduate School of Medical Sciences of Cornell University, New York, NY 10021, USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Fallas
authors.forename: Woelsung
authors.initials: W
authors.lastname: Yi
authors.forename: Nicole A
authors.initials: NA
authors.lastname: Draghi
authors.forename: Helen M
authors.initials: HM
authors.lastname: O'Rourke
authors.forename: Lisa K
authors.initials: LK
authors.lastname: Denzin
mesh_terms: D000818:Animals; D017951:Antigen Presentation; D001402:B-Lymphocytes / Q000276:immunology*; D003713:Dendritic Cells / Q000276:immunology*; D005786:Gene Expression Regulation / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D013154:Spleen / Q000166:cytology
chemical_list: C416186:H-2O antigen; C416189:H2-M antigens; D000949:Histocompatibility Antigens Class II; C474482:I-A(b) antigen, mouse