Antigen processing and presentation self mhc restriction
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Antigen Processing and Presentation, Self MHC Restriction. What Does The B Cell Immunoglobulin (Ig) Receptor Recognize?. Proteins (conformational determinants, denatured or proteolyzed determinants) Nucleic acids Polysaccharides Some lipids Small chemicals (haptens).

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What does the b cell immunoglobulin ig receptor recognize
What Does The B Cell Immunoglobulin (Ig) Receptor Recognize?

  • Proteins (conformational determinants, denatured or proteolyzed determinants)

  • Nucleic acids

  • Polysaccharides

  • Some lipids

  • Small chemicals (haptens)


Antigen processing and presentation
Antigen Processing and Presentation Recognize?

  • Fragmentation of protein into peptides

  • Association of peptide with an MHC molecule

  • Transport to cell surface for expression

  • Different cellular pathways for association of peptide with MHC class I and class II molecules


Class i mhc pathway
Class I MHC Pathway Recognize?

Peptide is presented

by MHC-I to CD8

cytotoxic T cell

Viral protein is made

oncytoplasmic

ribosomes

Plasma membrane

Globular viral

protein - intact

Peptide passes

with MHC from Golgi

body to surface

Proteasome degrades protein to

peptides

rER

Peptide associates

with MHC-I complex

Peptide transporter

protein moves peptide into ER

MHC class I alpha

and beta proteins

are made on the rER

Peptide with MHC

goes to Golgi body

Golgi body


Class ii mhc pathway

Peptide MHC-II Recognize?

complex is presented

to CD4 helper T cell

Class II MHC Pathway

Globular protein

CD4 helper T cell

Plasma membrane

Fusion of endosome

and exocytic vesicle

Endosome

Endosome fuses with

plasma membrane

Endocytosis

Immunodominant

peptide binds

to class II MHC

Lysosome

Exocytic vesicle fuses

with endosome

releasing Ii from αβ dimer

Protein is processed to

peptides in endosome

or lysosome

Golgi

body

Class II MHC

Synthesis

3 chains: α,β and Ii

α

β

Ii

Endoplasmic reticulum


Structure of class i mhc

α1 Recognize?

NH2

NH2

Alloantigenic

sites

β2

NH2

α2

COOH

CHO

α3

Disulfide bridge

Papain cleavage

Plasma membrane

OH

P

Cytoplasm

COOH

Structure of Class I MHC


Structure of class ii mhc

NH Recognize?2

NH2

α1

β1

CHO

CHO

α2

β2

CHO

Plasma membrane

Cytoplasm

COOH

COOH

Structure of Class II MHC


Points concerning antigen processing and presentation
Points Concerning Antigen Processing and Presentation Recognize?

1. Location of pathogen

  • viruses in cytosol, MHC class I pathway, Tc response

  • extracellular bacteria, MHC class II pathway, TH2 response, Ab formation

  • intracellular bacteria, MHC class II pathway, TH1 response


Points concerning antigen processing and presentation1
Points Concerning Antigen Processing and Presentation Recognize?

  • Peptides derived from both self and non-self proteins can associate with MHC class I and class II molecules.

  • Chemical nature of MHC groove determines which peptides it will bind.


Aspects of mhc
Aspects of MHC Recognize?

  • MHC molecules are membrane-bound. Recognition by T cells requires cell-cell contact.

  • Peptide from cytosol associates with class I MHC and is recognized by Tc cells. Peptide from vesicles associates with class II MHC and is recognized by TH cells.


Aspects of mhc continued
Aspects of MHC (continued) Recognize?

  • Although there is a high degree of polymorphism for a species, an individual has maximum of six different class I MHC products and only slightly more class II MHC products.

    A peptide must associate with a given MHC of that individual, otherwise no immune response can occur. That is one level of control.


Aspects of mhc continued1
Aspects of MHC (continued) Recognize?

  • Mature T cells must have a T cell receptor that recognizes the peptide associated with MHC. This is the second level of control.

  • Each MHC molecule has only one binding site. The different peptides a given MHC molecule can bind all types to the same site, but only one at a time.



Lymphatic Tissues Recognize?

Primary Lymph

Tissues

Secondary Lymph

Tissues

Bone

Marrow

Thymus Gland

Spleen

Lymph

Nodes

Bayer’s

Patches

Bursa of

Fabrices


Types of Abs Recognize?

Against Same Ag

Allotype

Idiotype

Isotype

Different classes

IgG, IgM, IgA

IgD, IgE

Different Variable

For the same Ag

On Same Class

Different

Amimals

e.g.: Horse

to Human


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