Ectopic expression of HLA-DO in mouse dendritic cells diminishes MHC class II antigen presentation.
The MHC class II-like molecule HLA-DM (DM) (H-2M in mice) catalyzes the exchange of CLIP for antigenic peptides in the endosomes of APCs. HLA-DO (DO) (H-2O in mice) is another class II-like molecule that is expressed in B cells, but not in other APCs. Studies have shown that DO impairs or modifies the peptide exchange activity of DM. To further evaluate the role of DO in Ag processing and presentation, we generated transgenic mice that expressed the human HLA-DOA and HLA-DOB genes under the control of a dendritic cell (DC)-specific promoter. Our analyses of DCs from these mice showed that as DO levels increased, cell surface levels of A(b)-CLIP also increased while class II-peptide levels decreased. The presentation of some, but not all, exogenous Ags to T cells or T hybridomas was significantly inhibited by DO. Surprisingly, H-2M accumulated in DO-expressing DCs and B cells, suggesting that H-2O/DO prolongs the half-life of H-2M. Overall, our studies showed that DO expression impaired H-2M function, resulting in Ag-specific down-modulation of class II Ag processing and presentation.
Fallas
Jennifer L
JL
Cell Biology and Genetics Program, Weill Graduate School of Medical Sciences, Cornell University, New York, NY 10021, USA.
Tobin
Helen M
HM
Lou
Olivia
O
Guo
Donglin
D
Sant'Angelo
Derek B
DB
Denzin
Lisa K
LK
D000199:Actins / Q000276:immunology; D000818:Animals; D017951:Antigen Presentation / Q000235:genetics / Q000276:immunology*; D000941:Antigens / Q000276:immunology; D000944:Antigens, Differentiation, B-Lymphocyte / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism; D039521:CD11c Antigen / Q000235:genetics; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000276:immunology* / Q000378:metabolism; D005813:Genes, Synthetic; D006183:H-2 Antigens / Q000276:immunology / Q000378:metabolism; D006681:HLA-D Antigens / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D000949:Histocompatibility Antigens Class II / Q000276:immunology / Q000378:metabolism; D006801:Humans; D006825:Hybridomas / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009113:Muramidase / Q000276:immunology; D010047:Ovalbumin / Q000276:immunology; D010446:Peptide Fragments / Q000276:immunology; D011401:Promoter Regions, Genetic / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000502:physiology; D001613:beta 2-Microglobulin / Q000276:immunology
D000199:Actins; D000941:Antigens; D000944:Antigens, Differentiation, B-Lymphocyte; D039521:CD11c Antigen; D006183:H-2 Antigens; C489629:H-2A(b) antigen, mouse; C489628:H-2M antigen, mouse; D006681:HLA-D Antigens; C046148:HLA-DO antigens; D000949:Histocompatibility Antigens Class II; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; C108503:antigen H-2A(k); D001613:beta 2-Microglobulin; C045084:invariant chain; C066759:hen egg lysozyme peptide (46-61); D010047:Ovalbumin; D009113:Muramidase