Antigen presenting cells and antigen presentation
1 / 45

Antigen-presenting cells and antigen presentation - PowerPoint PPT Presentation

  • Uploaded on

Antigen-presenting cells and antigen presentation. Contents. 1.Nature of antigen-presenting cells 2. Antigen processing and presentation. Antigen Presenting Cell (APC). Section 1 Nature of antigen-presenting cells.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about ' Antigen-presenting cells and antigen presentation' - mave

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript


1.Nature of antigen-presenting cells

2. Antigen processing and presentation

Section 1 Nature of antigen-presenting cells

Antigen-presenting cells (Antigen Presenting Cell, APC) are the immunocytes that can uptake, process and present antigens to lymphocytes.

Professional APC

Dendritic cells, mononuclear phagocyte system, B cells, and APC that constitutively express MHC II molecules

Non-professional APC

DC are the most powerful APC in vivo, which can effectively stimulate naïve T cells to proliferate. Yet M and B cells can only stimulate activated or memory T cells.

Multiple hematopoietic stem cell

Lymphoid stem cell

Myeloid stem cell


Myeloid DC


NK cell

Lymphoid DC

T cell

B cell


Myeloid DC

Origination of dendritic cells(DC)

Tissue distribution

Lymphoid DC:interdigitating DC, marginal DC

Non-lymphoid DC: interstitial DC, LC, gastrointestinal epithelial DC

Humoral DC: veiled cell

Blood DC

Immature DC

Distribution: many solid organs and non lymphatic epithelia

Major role: uptake and process antigen

Normally, most DC are immature DC.

Mature DC

Distribution: T lymphocyte areas in lymph node, spleen, and Peyer’s node, blood

Characteristics: abundantly express MHC II、MHC I、CD80、CD86、CD40、ICAM-1、HSP、CD1a、CD11c、CD83

Major role: antigen presentation, present peptide:MHC complex to T cells

Antigen uptaking pathways by DC

  • macropinocytosis

  • receptor-mediated endocytosis

  • phagocytosis

2. Mononuclear macrophages


Origination and distribution

Bone marrow pluripotent stem cells-mononuclear cells-macrophages

Antigen processing and presentation of M

  • endocytosis or internalization:

  • phagocytosis

  • Pinocytosis

  • receptor-mediated endocytosis

    Only those M in vigorous metabolism have the capacity of antigen presentation.


mIg mediated endocytosis

Complement receptor mediated endocytosis


Fc receptor mediated endocytosis

Uptake of exogenous antigens

3 B lymphocytes

Receptor-mediated endocytosis

Non-specific pinocytosis

Dendritic cell


B cell

Staining of APC

DC capture antigens


Receptor-mediated endocytosis


Mononuclear macrophage capture antigens:



Receptor-mediated endocytosis

B cells captureantigens:

Non-specific pinocytosis

Antigen-specific receptor mediated

2. Antigen processing

1、Endogenous pathway

Antigens: intracellular synthesized antigens

Presenting molecules:MHC-I

Processing region: Proteosome (polyubiquitination)

Binding region: ER

Cell surface


Golgi complex

Endoplasmic reticulum


MHC Ia chain

Degraded antigens


Endogenous antigens

Processing and presentation of endogenous antigens

(1) Production of endogenous antigenic peptide

Ubiquitination of endogenous antigens

Degradation of endogenous antigens in proteosome

Peptides containing 8-12 amino acidresidues

(2) Transportation of endogenous antigenic peptide

Endogenous antigenic peptide enter endoplasmic reticulum:

Transporter associated with antigen processing(TAP)

3) MHC class I molecules peptide loading

Class I molecules associate with chaperon:

Bind to endogenous antigenic peptides

Enter Golgi complex to undergo glycosylation modification

Traffick to cell surface in exocytic vesicles and recognized by CD8+ T cells


Antigen-MHC class 1 molecule complex

β2 microglobulin

Heavy chain of antigen-MHC class 1 molecule

Golgi complex

β2 microglobulin


Antigenic peptide

Endogenous antigen

Presentation of endogenous antigens


2. Presenting pathway of exogenous antigens(Exogenous pathway)

Antigen: extracellular antigens

Presenting molecules: MHC-II

Processing region: endosome

Binding region: MIIC、CIIV

Cell surface pathway)

Exogenous antigens


Early endosome

Late endosome

Antigen degradation

Golgi complex

MHC class 2 molecule

Ii chain

Endoplasmic reticulum

Processing and presentation of exogenous antigens

Antigen processing compartment pathway)


MHC class II、HLA-DM, and exogenous antigenic peptide are found in abundance.

pathway)2)Degradation of protein antigen

Peptides containing 12-20 amino acid residues



MHC class II molecules are transported from ER to endosome. pathway)


Ia associated invariant chain(Ii chain):

Class II associated invariant chain peptide (CLIP)

Form nonamer with ,  chain

Enter endosome through trans-Golgi network

Function of Ii pathway)

To prevent degradation of MHC class II molecule during its transportation

CLIP binds to the grooves in MHC class II molecule

pathway)4)Ii degradation in endosome

(5)Class II molecules peptide loading

pathway)6)Presentation of exogenous antigens

Exocytic vesicles

Expressed on APC

Recognized by CD4+ T cells

Antigen pathway)


Antigenic peptide-MHC class 2 molecule complex



B cell



Golgi complex


Antigenic peptide-MHC class 2 molecule complex

αβIi complex

Ii chain

Presentation of exogenous antigens

Comparison of endogenous and exogenous antigen-presenting pathway

Characteristics Endogenous pathway exogenous pathway

Presenting molecule MHC-I MHC-II

Responding T cells CD8+ T cells CD4+ T cells

Antigen resources endogenously synthesized exogenous uptaken

Synthesizing region

of antigen peptides proteosome endosome

Chaperon Calnexin, TAP, tapasin Calnexin, Ii chain

Presenting cells all nucleated cells professional APC

3. Antigen presentation pathway

1. Basic procedure of antigen presentation

CD8+ T cells pathway

Tumor cells

2.Cross presentation of antigens by MHC molecules pathway

(Cross priming pathway)

  • Master cell types, definition and characteristics of APC pathway

  • Master types of professional APC

  • Master the pathway and procedure of exogenous and endogenous antigen presentation

  • Familiarize antigen cross presentation

  • Understand the distribution and characteristics of various kinds of professional APC

  • Understand development, differentiation, maturation and migration of DC