Antigen recognition by T lymphocytes

Dr. Glorivee Rosario-Pérez

BIOL 4056

Parham P. (2009). The Immune System. Third Edition. Garland Publishing, New York.

T cell receptor diversity

T cell receptor vs ImmunoglobulinT cell receptor Immunoglobulin

Membrane-bound glycoprotein Membrane-bound glycoprotein

It is composed of two different chains and has one antigen-binding site.

It is composed of two different chains and has one antigen-binding site.

Always membrane bound

No secreted form

Membrane bound

Secreted form

Variable region (binds antigen)

Constant region

Variable region (binds antigen)

Constant region

During T cell development, gene rearrangement produces sequence variability in the variable regions of the T cell receptor.

During B cell development, gene rearrangement produces sequence variability in the variable regions of the immunoglobulin.

After the T cell is stimulated with antigen, there is no further mutation in the antigen-binding site and there is no switching of constant region isotype.

After the B cell is stimulated with antigen, occur mutation in the antigen-binding site and switching of constant region isotype.

T cell receptors are used only as receptors to recognize antigen

Immunoglobulin serve as both recognition and effector molecules

Figure 3-11

T cell receptor

Figure 4-11

Chromosome 14

Chromosome 7

T cell receptor

T cell receptor diversity

Figure 4-13

T cell receptor complex

Two classes of T cell receptors

Antigen processing and presentation

Antigen processing and presentation complejo de inmunocompatibilidad

T cell : CD4 and CD8

CD8

Are cytotoxic.

Their main function is to kill cells that have become infected with a virus or some other intracellular pathogen.

This response prevents the multiplication of the pathogen and further infection of healthy cells.

CD4

Help other cells of the immune system to respond to extracellular sources of infection.

Two subclasses: TH1 – activate tissue macrophages to

phagocytose and kill extracellular pathogens, and to secrete cytokines and other active molecules that affect the course of the immune response.

TH2 – involved mainly in stimulating B cells to make antibodies, which bind to extracellular bacteria and virus particles.

T cells function : CD4 and CD8

MHC

MHC class I and II

Figure 3-20

Figure 3-21

Figure 1-27

Figure 1-28

Figure 1-29 part 1 of 2

Figure 1-29 part 2 of 2

Figure 1-30

Figure 1-31 part 1 of 2

Figure 1-31 part 2 of 2

Peptides and MHC I / MHC II

Figure 5-2

Peptides and MHC I

Peptides and MHC I

Figure 5-3 part 1 of 2

Peptides and MHC I cont.

Peptides and MHC II

Figure 5-7

Peptides and MHC II cont.

Figure 5-8

Figure 5-10

MHC and cells

MHC complex

Human MHC I and II isotypes

Figure 5-13

Figure 4-25