Interaction of HLA-DR and CD74 at the cell surface of antigen-presenting cells by single particle image analysis.
Major histocompatibility complex (MHC) class II-associated antigen presentation involves an array of interacting molecules. CD74, the cell surface isoform of the MHC class II-associated invariant chain, is one such molecule; its role remains poorly defined. To address this, we have employed a high-resolution single-particle imaging method for quantifying the colocalization of CD74 with human leukocyte antigen (HLA)-DR molecules on human fibroblast cells known for their capacity to function as antigen-presenting cells. We have also examined whether the colocalization induces internalization of HLA-DR using HA(307-319), a "universal" peptide that binds specifically to the peptide-binding groove of all HLA-DR molecules, irrespective of their alleles. We have determined that 25 ± 1.3% of CD74 and 17 ± 0.3% of HLA-DR are colocalized, and the association of CD74 with HLA-DR and the internalization of HLA-DR are both inhibited by HA(307-319). A similar inhibition of HLA-DR internalization was observed in freshly isolated monocyte-derived dendritic cells. A key role of CD74 is to translocate HLA-DR molecules to early endosomes for reloading with peptides prior to recycling to the cell surface. We conclude that CD74 regulates the balance of peptide-occupied and peptide-free forms of MHC class II at the cell surface.
School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester C04 3SQ, UK.
Ioannis
I
Karakikes
Ian E G
IE
Morrison
Peter
P
O'Toole
Gergana
G
Metodieva
Cristina V
CV
Navarrete
Jesus
J
Gomez
Jose M
JM
Miranda-Sayago
Richard J
RJ
Cherry
Metodi
M
Metodiev
Nelson
N
Fernandez
D000328:Adult; D000465:Algorithms; D000938:Antigen-Presenting Cells / Q000378:metabolism*; D000944:Antigens, Differentiation, B-Lymphocyte / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects; D005434:Flow Cytometry; D031541:Fluorescence Resonance Energy Transfer; D006684:HLA-DR Antigens / Q000235:genetics / Q000378:metabolism*; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000378:metabolism / Q000494:pharmacology; D000949:Histocompatibility Antigens Class II / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D021621:Imaging, Three-Dimensional; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence / Q000379:methods*; D010446:Peptide Fragments / Q000378:metabolism / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects
D000944:Antigens, Differentiation, B-Lymphocyte; D006684:HLA-DR Antigens; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D000949:Histocompatibility Antigens Class II; D010446:Peptide Fragments; C081942:influenza hemagglutinin (307-319); C045084:invariant chain