Immunology and Adaptive Immunity

Question 1

How is the immune system effective in fighting off foreign bodies?

Answer 1

Discrimination of self from non-self

Question 2

What is innate immunity?

Answer 2

Non-specific, instinctive, short term lasting, present from birth immunity focused around physical/chemical barriers and phagocytosis

Question 3

What physical barriers are used in innate immunity?

Answer 3

Skin, mucociliary escalator, gastric acid, hairs, lysozymes (Destroy bacterial cell wall)

Question 4

What is adaptive immunity?

Answer 4

Specific immunity requiring lymphocytes, memory and quicker response

Question 5

What are the different examples of leucocytes?

Answer 5

PM Leucocytes: Neutrophils, Basophils, Eosinophils

MN Leucocytes: Monocytes, B Lymphocytes, T Lymphocytes

Question 6

What are the functions of T helper cells?

Answer 6

T1 (CD4): Helps immune response against intracellular pathogens, secreting cytokines
T2(CD4): Helps produce antibodies against EC pathogens, secreting cytokines

Question 7

What is the function of Cytotoxic T cell (CD8)?

Answer 7

Kills cells directly by binding to antigens, inducing apoptosis

Question 8

What is the role of a T reg (FoxP3)?

Answer 8

Regulate immune response

Question 9

What cells express MHC1 and MHC2?

Answer 9

MHC1: All nucleated e.g. Intracellular antigen
MHC2: Antigen presenting cells ONLY e.g. macrophage, B cells, dendritic (EC antigen)

Question 10

What T cell binds to each MHC?

Answer 10

MCH1: Cytotoxic T cells (CD8)
MCH2: Helper T Cells (CD4)

Question 11

What does a T Helper cell bind to?

Answer 11

A T cell receptor which is bound to antigen epitope to an MHC2 on an APC

Question 12

Which interleukin is secreted when helper T cell is bound to T cell receptor?

Answer 12

IL-2: Binds to IL-2 receptor on T cell and produces positive feedback mechanism leading to division and differentiation

Question 13

What are 3 functions of antibodies?

Answer 13

1) Neutralise toxins
2) Opsonisation
3) Activate classical complement system

Question 14

How does a helper T cell bind to a B cell?

Answer 14

B cell AB binds to antigen ->Phagocytosis -> Epitope on B-cell surface bound to MHC2 -> TH2 binds to B-cells -> Cytokine secretion induces B-cell clonal expansion -> Differentiation into plasma and memory B cells

Question 15

What are the most common immunoglobulins?

Answer 15

IgG and IgM (IgA found in breast milk/other secretions)

Question 16

Which region of an antibody binds to antigens? (Which AB region to B cells?)

Answer 16

Fab region

Fc Region

Question 17

What are 4 types of cytokines?

Answer 17

1) Interferons
2) Interleukins
3) Colony Stimulating Factors
4) Tumour necrosis factors

Question 18

What do each of the 4 cytokines do?

Answer 18

1) Interferons: Produce antiviral proteins
2) Interleukins: Cell division and differentiation
3) CSF: Division and differentiation of bone marrow stem cells
4) TNF Mediates inflammation and cytotoxic reactions

Question 19

What is the role of chemokines?

Answer 19

Chemokines attract leucocytes to sites of infection

Question 20

What are the 3 main outcomes of complement system activation?

Answer 20

Proteins derived from the liver

1) pathogen lysis
2) Increased phagocytosis
3) Activation of leukocytes

Question 21

What activates the classical complement pathway?

Answer 21

Antibodies

Question 22

What is the classical complement pathway?

Answer 22

1) C1 cleaves C4 –> C4a, C4b
2) C4b binds to C2b forming C4b2b. C4b2b = C3 convertase and responsible for C3-> C3a and C3b
3) C4b2b binds to C3b forming C4b2b3b
4) C5,6,7,8,9 bind –> MAC formation
[C1 inhibitor prevents excessive activation of pathway]