BASIC SHAPES PRESENTATION

Info

Antigens = foreign molecules, often proteins, present on the surface of pathogens such as bacteria, viruses and infected cells.

ANTIGEN

RECOGNITION

Antigens

→ key process of the immune system→ distinguish foreign substances from normal body components → several stages and immune molecules involved

01

FIRST PART WITH THE APCs

APC = Antigen-Presenting Cell

Capture and analysis of the foreign (or not) compound

• Immune cells capture the compound

• Pattern Recognition Receivers (PRRs) detect pathogen-associated molecular patterns (PAMPs)

• Triggering the immune response

Antigens treatment

• Breaking down antigens into fragments thanks to proteasomes

• Positioning the antigenic peptides (the fragments thus formed) on the APC surface.

• Associating the peptides with MHC (Major Histocompatibility Complex) class II molecules

• Presenting fragments to T lymphocytes

via MHC complexes

02

SECOND PART WITH THE T LYMPHOCYTES

Antigen recognition by T lymphocytes

• This recognition depends on a precise fit between the structure of the antigen and that of the T cell TCRs.

T lymphocyte activation

• Intracellular events (cytokine release and cell proliferation)

• Cell division to create a population of activated T lymphocytes

• Two distinct groups of T lymphocytes: the cytotoxic and the helper cells

• Destruction of pathogen-infected cells and regulation of the immune response

T cell activation process

T lymphocytes conservation

• Transformation of T lymphocytes into memory lymphocytes to provide a "reserve" of T cells in the event of a new infection with the same virus.

To sum up...

Antigen recognition...

→ is essential for triggering a specific and effective immune response against pathogens→ is crucial for defending the body by fighting infections and diseases → enables targeting and neutralizing only foreign invaders while preserving the body's healthy cells and tissues