Intercellular exchange of class II MHC complexes: ultrastructural localization and functional presentation of adsorbed I-A/peptide complexes.
Activated rat T cells, like human T cells, synthesize class II MHC glycoproteins (MHCII) and absorb MHCII from neighboring T cells. This study focused on interactions of myelin basic protein (MBP)-specific T cells that either synthesized MHCII or absorbed MHCII during activation to assess cellular structures associated with presentation of functional MHCII/peptide complexes. Synthesis of MHCII by CD4(+)TCR(+) T cells involved I-A(+) multivesicular MHC class II-like compartments (MIIC), release of MHCII(+) vesicles, and expression of MHCII on a dendritic arborization. T-cell-mediated adsorption of MHCII was a saturable process that required close cell proximity, actin polymerization, and a permissive temperature. Adsorbed MHCII existed on vesicles that were intimately associated with the responder cell membrane. T cells bearing adsorbed vesicular MHCII presented antigen and were specifically lysed by CD4(+) T cell responders, but when labeled with anti-MHCII antibody were not susceptible to complement-mediated lysis. In summary, this study reveals vesicular compartments associated with synthesis and intercellular exchange of functional MHCII/peptide complexes.
Patel
D M
DM
Department of Microbiology and Immunology, East Carolina University School of Medicine, Greenville, North Carolina 27858-4354, USA.
Dudek
R W
RW
Mannie
M D
MD
D000818:Animals; D017951:Antigen Presentation; D000938:Antigen-Presenting Cells / Q000276:immunology / Q000648:ultrastructure; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D002450:Cell Communication; D002999:Clone Cells; D003165:Complement System Proteins / Q000276:immunology; D022162:Cytoplasmic Vesicles / Q000737:chemistry / Q000648:ultrastructure; D004705:Endocytosis; D000949:Histocompatibility Antigens Class II / Q000032:analysis* / Q000378:metabolism*; D008213:Lymphocyte Activation; D046911:Macromolecular Substances; D051379:Mice; D004676:Myelin Basic Protein / Q000276:immunology; D010455:Peptides / Q000276:immunology; D051381:Rats; D013601:T-Lymphocytes / Q000276:immunology* / Q000648:ultrastructure; D014407:Tumor Cells, Cultured
D000949:Histocompatibility Antigens Class II; D046911:Macromolecular Substances; D004676:Myelin Basic Protein; D010455:Peptides; D003165:Complement System Proteins