Antigen Presentation
Fundamentals I for Dentistry & Optometry
Textbook:
Medical Microbiology, 6th Edition, Murray
Chapter 11
Jim Collawn, MCLM 350
jcollawn@uab.edu
934-1002
Study Objectives
1. Compare and contrast class I and class II MHCrestricted responses with regard to
A. source of antigens
B. antigen processing requirements
C. role of chaperones
D. types of T cell involved
2. Discuss the invariant chain’s role in the
demarcation between class I and class II MHCrestricted responses.
3. Discuss HLA-DM’s possible role in antigen
processing.
Humoral
and
Cellmediated
Immune
Responses
Major Players in T cell Responses
T lymphocyte and Macrophage (right)
Types of T cells
1. Cytotoxic T cells (CTLs)
A. Kill virally infected cells
B. Kill cells containing cytosolic
bacteria
C. Kill tumor cells
2. Inflammatory T cells (TH1)
A. Activate macrophages to kill
intracellular bacteria
3. Helper T cells (TH2)
A. Activate B cells to make antibody
Schematic Diagrams of MHC class
I and class II Molecules
MHC class I (top view)
Major Histocompatibility Complex
HLA-DR1 (blue) and HLA-A2
MHC class I
MHC class II
Anchor Residues for MHC class I
peptides
Conformation of Peptides Bound to
MHC class I
Solvent-accessible Area of H-2Kb
Anchor Residues for MHC class II
peptides
Antigen Processing is Necessary for Helper T
cell Activation
Antigen-presenting Cells
(MHC Class II-positive cells)
HLA-DR, HLA-DP, HLA-DQ
Target Cells
(MHC Class I-positive cells)
HLA-A, HLA-B, HLA-C
All nucleated cells
Degradation of Intracellular Proteins
Transporter associated with Antigen
Processing
Generation of Peptide-class I MHC Complexes
Demarcation
between MHC
class I and class
II Processing
Pathways
Cytosolic and Endocytic Pathways for Antigen
Processing
Assembly of MHC class II Molecules
Study Objectives
1. Compare and contrast class I and class II MHCrestricted
responses with regard to
A. source of antigens
B. antigen processing requirements
C. role of chaperones
D. types of T cell involved
2. Discuss the invariant chain’s role in the
demarcation between class I and class II MHCrestricted responses.
3. Discuss HLA-DM’s possible role in antigen
processing.
Sample Questions
•
•
•
•
The MHC class II molecule
– is associated with ß-2 microglobulin.
– binds peptide antigens from the endogenous pathway.
– is associated with the invariant chain.
– is expressed on all cell types.
Exogenous antigens
– are taken up by cells through endocytosis or phagocytosis.
– are bound to MHC class I molecules.
– are processed by the proteasome.
– become associated with MHC class I molecules in the endoplasmic
reticulum.
Sample Questions
•
•
•
HLA-DR
– presents antigens to cytotoxic T cells.
– is a chaperone that facilitates CLIP removal and peptide binding.
– is an MHC class II molecule.
– binds to endogenous antigens.
The proteolytic activity necessary for the generation of MHC class IIassociated peptides is provided by
– the proteasome.
– the lysosome.
– furin.
– the endoplasmic reticulum.