Thomas Vorup-Jensen, Ph.D. Dept. of Biomedicine Aarhus University Denmark

Antigen optag & præsentation til T lymfocytter Du skal kunne: Redegøre for de væsentligste cellulære processer, der bringer antigen ind i lymfoidevæv Beskrive centrale molekyler, der indgår i præsentationen af antigen på overfladen af APCer til T celler Beskrive centrale molekylære mekanismer, der indgår i processeringen af antigener

K. Inaba et al., J. Exp. Med. (1984) 160:858 Dendritic cells: a veiled membrane that permits efficient adhesion to lymphocytes? K. Inaba et al., J. Exp. Med. (1984) 160:858

Labelled DCs and T cells can be monitored by multiphoton intravital microscopy (IVM) T cells DC Collagen Mempel et al. (2004) Curr. Opin. Immunol. 16:406-17 Mempel et al. (2004) Nature 427:154-9

Antigen optag & præsentation til T lymfocytter Professionelle APC inkluderer macrofager, B lymfocytter og dendritiske celler Umodne dendritiske celler transportere antigen ind i lymfeknuderne til ”T celle zonerne” Modningsprocessen involverer forøget ekspression af MHC

Targeted by ”biologicals” T cell APC Targeted by ”biologicals”

Figure 1 Formation of the immunological synapse. Formation of the immunological synapse. 2B4 T cells in contact with a supported planar bilayer containing Oregon green Ek(MCC88-103)-GPI at 80 molecules per square micrometer and Cy5 ICAM-1–GPI at 200 molecules per square micrometer. (A) Images of contact formation (IRM) at five time points. IRM shows contacts as dark gray on a light background. (B) Images of MHC-peptide (green) and ICAM-1 (red) accumulation. (C) Density of accumulated Ek(MCC88-103). (D) Total accumulated Ek(MCC88-103). (E) Density of accumulated ICAM-1. The accumulated ligand measurements were on the entire area where the accumulated ligands exceeded the density in the bilayer (40). Original image elements = 0.44 μm2. Representative of four experiments with 2B4 and 3.L2. A Grakoui et al. Science 1999;285:221-227 Published by AAAS

Signalling occurs by redistribution of kinases and phosphotases in cell-cell contact. (fortsættes i Forelæsning 6 ”Celle-medieret immunrespons”….)

Cell membrane proteins involved in the immunological synapse formation are drug targets for anti inflammatory therapy (anti CD11a ”LFA-1”) (anti CD2) (blocks TNF function) (anti TNF) (anti TNF) Treatments targeting CD4, CD8, and CD3 are also on the market… MacDonald & Burden (2007) Postgrad Med J 83:690–697.

Antigen optag & præsentation til T lymfocytter Den immunologiske synapsedannelse er central i præsentationen af antigen til T celler (se også Kap. 3, f.eks. Fig. 5-3) I forbindelse med antigenpræsentation ”omorganiseres” membran proteiner i T cellens cellemembran Membranproteiner vigtige for antigenpræsentation er drug targets!

The HLA loci are highly polymorphic

”I'm sorry, but I just don't understand anything in biology unless I know what it looks like."

Antigen optag & præsentation til T lymfocytter MHC klasse I og II er membran proteiner, der har en peptid- bindende kløft i NH2-terminalen: eet MHC klasse molekyle kan Binde til mange peptider men kun til ét ad gangen! HLA loci er polymorfe og med udtrykt co-dominant=> stor variation i udtrykket af MHC blandt individer MHC I udtrykkers på alle kerneholdige celler og MHC II udtrykkes på profesionelle APCer.

Macrophages (MØ) produce more proteases than dendritic cells or B lymphocytes Fig. 1. DC and B cells have lower amounts of lysosomal proteases than MØs. (A) The indicated proteases were detected by immunofluorescence on frozen sections of spleen (left) and lymph node (right) from C3H/HeJ mice. AEP stands for asparagine endopeptidase or legumain. (B) Detection of lysosomal proteases by Western blot. DCs (S-DC) and B cells (S-B) were isolated from spleen with magnetic microbeads conjugated to a monoclonal antibody against CD11c (DCs) or CD19 (B cells). MØs (P-MØ) were isolated by adherence to plastic culture dishes from a peritoneal lavage obtained 3 days after injection of 2 ml of 3% thioglycollate. The asterisks indicate the immature, incompletely cleaved forms of the corresponding enzymes. AEP: asparagine endopeptidase; cat:cathepsin Delamarre et al. Science (2005) 307:1630-1634

Antigen optag & præsentation til T lymfocytter

SEB Peptide HLA-DR1 Jardetzky et al. Nature (1994) 368:711-8

Antigen optag & præsentation til T lymfocytter Nu kan du: Redegøre for de væsentligste cellulære processer, der bringer antigen ind i lymfoidevæv DC’ere transportere Ag fra infektionszoner til lymfeknuderner DC’ere er specialiserede i denne funktion sammenlignet med andre APCere Beskrive centrale molekyler, der indgår i præsentationen af antigen på overfladen af APCer til T celler TCR, MHC & andre molekyler i den immunologiske synapse cellulært udtryk Organiseringen af HLA loci Overordnede strukturelle aspekter af MHC binding af peptid Beskrive centrale molekylære mekanismer, der indgår i processeringen af antigener MHC klasse I pathway MHC klasse II pathway I tvivlstilfælde kontakt: Thomas Vorup-Jensen, Bartholin Bygn 4. etage (rum 433) Tlf. 8716 7853; e-mail vorup-jensen@microbiology.au.dk Skype: thomas.vorup.jensen