Wk 9- Adaptive Immune System

The Adaptive immune system is: The - line of defence Is s? in action, not localised Has a - and reacts forcefully against a - infection

Adaptive immunity and Antigens: Foreign cells have - on their surface. These - are recognised by cells of the adaptive immune system = - induce an adaptive immune response > the production of anti? Our bodies possess their own self anti- (A,B,Rh) Most antigens are p? or polysaccharides.

Divisions of the adaptive immunity: A.I can be divided into 2 groups • Cell Me? immunity and • H? immunity (fluid)

Divisions A.I • Cell mediated Immune function performed by activated ? Destroys intracellular pa? cancerous cells and fo? cells.

Divisions A.I • Humoral immunity Antibody mediated immunity = i? function performed by - Removes extra cellular pa?

Lymphocytes: Humans carry around 1? weighing 1 -- What are the 3 classes of lymphocytes? 1. -- cells 2. - cells: 3 types= cytotoxic (CD8) and helper ?cells (CD4) memory (thymus) 3. - cells (bone marrow)

T and B cell receptors: Each individual T or B cells produces receptors for only - antigen T cells have additional receptors which are proteins. C?? C?? B = 1 antigen T = 1 antigen ,2 proteins

Our cells display their own self antigens. Human self antigens = MHC molecules What does MHC stand for? Major his? Com? MHC can be divided into class 1 and class 2

MHC classes: 1 endogenous antigens Class 1 N? cells Incorporate foreign anti? after infection Labels cell as infected to cytotoxic ? cell (CD?)

MHC classes: 2 exogenous antigens Class 2 Displayed by antigen p- cells (APC) Engulf and break down pathogenic antigen (Mac? Den? cells and ? Cells) Present antigen MHC complex to Helper ? cells (CD?)

Memory T cells: Produced during ? cell activation~ cloned Remain in l? tissue Very fast reaction to second exposure of infection/ a?

B cell activation: Antigen binding Activation via ? T cells Division and differentiation Produce ~ 1. Pl? cells (antibodies) 2. M? cells

B cell activation: • Plasma cells Secrete antibodies 2000/second/cell Short lifespan last 4-? Days Peak plasma antibody concentration at -0 days • Memory B cells Remember ? for fast future activation

Antibodies: Immunoglobulins (Igs) Y shaped Target extra cellular pathogens and t? 5 mechanisms Agglutination ~ antibodies clump antigens together to enhance pha? Opsonisation~ immunoglobulin coats anti? and binds phagocytes enhancing pha? Neutralisation~ antibodies bind pathogenic components of t? and block toxic effects Complement activation~ antibodies activate complement pr? leading to cell lysis Inflammation ~ immunoglobulin binds ma? cells and basophils triggers release of ? response