Adaptive immune system part 2

Question 1

Helper T cells

Answer 1

-CD4 molecule, helper T cell and MHC II molecule bind.
-macrophage releases interleukins which bind to receptors on helper T cells
- T helper cells divide into two daughter cells
- help B and T cells to be activated

Question 2

B cells

Answer 2

Phagocytoses same antigen as Helper T cell
Presented on surface of B cell by MHC class II molecule
T-cell receptor binds to MHC class II / antigen complex
Aided/co-stimulated by CD4 molecule
Co-stimulated by ILs (TH cell)
Stimulates B cells to divide
some differentiate into plasma cells to produce antibodies

Question 3

Antibody immunity

Answer 3

Proteins
Y-shaped molecules
consisting of four polypeptide chains: two identical heavy chains and two identical light chains
Variable region (top)
Antigen binding site
Constant regions
Immunoglobulins (Ig)
IgG, IgM, IgA, IgE, IgD

Only affect extracellular antigens

Question 4

describe the Primary response

Answer 4

First exposure to antigen
B cell undergoes several divisions
Forms plasma cells and memory B cells
Plasma cells produce antibodies
Normally takes 3–14 days
Normally develops disease symptoms
pathogen has had time to cause tissue damage
After antigen destroyed antibodies degrade and plasma cells die
IgM

Question 5

Secondary immune response

Answer 5

Secondary response
Previously exposed to antigen
Memory B cells quickly divide to form plasma cells
Quickly produce antibody
Makes more memory cells
Quicker to produce antibodies
More plasma cells/antibodies
Memory cells persist for long time
IgG

Question 6

effects of antibodies

Answer 6

Inactivate antigen: antibody binds to an antigen or when many antigens are bound together

Activates Complement Cascade: Antigen binds to antibody. Antibody can then activate complement proteins  inflammation, attracts WBC and lyses cells

Initiates release of inflammatory mediators: Antibody binds to mast cell /basophil. Triggers degranulation

Facilitate Phagocytosis: Antibody binds to antigen. Macrophages attaches to Fc of the antibody and phagocytoses both the antibody and the antigen

Antibody dependent cellular activity : Activates cytotoxic cell responses. Cytotoxic cells release chemicals that destroy the antibody-bound antigen