Adaptive Immunity

Question 1

Table to compare innate v adaptive immunity

Answer 1

Question 2

Characteristics of adaptive immunity

Answer 2

-specificity and diversity
-adaptation
-memory
-discrimination between self and non-self through self-tolerance

Question 3

When is adaptive immunity triggered?

Answer 3

When invading pathogen persists and requires a more specialised and targeted response

Question 4

Adaptive immunity - specificity and diversity

Answer 4

Antigen-specific lymphocytes (T cells and B cells) carrying antigen-specific receptors (TCR,BCR) —> immune response is specific to individual antigens

Question 5

Adaptive immunity - adaptation

Answer 5

The immune system functions only on contact with the antigen and its quality and quantity can be modified (adapted)

Question 6

Adaptive immunity - memory

Answer 6

Previous contact with an antigen changes the subsequent response both qualitatively and quantitatively

Question 7

Primary lymphoid organs

Answer 7

Origin of lymphocyte - bone marrow
Development and maturation

Question 8

Where are B cells produced?

Answer 8

Bone marrow

Question 9

Where are T cells produced? And matured?

Answer 9

Bone marrow by hematopoietic stem cells
Matured in thymus

Question 10

What are secondary lymphoid organs?

Answer 10

Where mature lymphocytes encounter their antigen

Question 11

B cell development in bone marrow

Answer 11

1.start in bone marrow Development—> immature B cell, no BCR yet
2.immature B cell —> displays a BCR
3.selection process —> learns to ignore self-antigens
4.mature B cells leave bone marrow to secondary lymphoid organs

Question 12

T cell development in Thymus

Answer 12

-T-cell precursors travel from the bone marrow to develop in the thymus
-mature T cells leave the thymus and travel to secondary lymphoid tissues

Question 13

T cell development in Thymus

Answer 13

1.arrival in thymus - immature, no TCR
2.cortex stage - acquired TCR and expresses both CD4 and CD8 (double-positive)
3.selection process - learns self vs non-self
4.medulla stage - becomes single-positive (CD4 or CD8)
5.exit to secondary lymphoid organs ready to function

Question 14

Example of secondary lymphoid tissues

Answer 14

Lymph node, spleen

Question 15

Lymphocytes in histology

Answer 15

-in blood, small cells, containing a single large round nucleus and a rim of cytoplasm

Question 16

What immunity are T cells involved in?

Answer 16

Cell-mediated immunity

Question 17

What immunity are B cells involved in?

Answer 17

Humoral immunity

Question 18

Innate response of extracellular pathogens

Answer 18

Phagocytosis, degranulation, complement system

Question 19

Adaptive response of extracellular pathogens

Answer 19

B cells produce antibody with help of T helper

Question 20

Innate response of intracellular pathogens

Answer 20

NK cell killing

Question 21

Adaptive response of intracellular pathogens

Answer 21

Cell killing by cytotoxic T cell

Question 22

Why are different immune responses needed?

Answer 22

Extracellular and intracellular pathogens activate different components of the immune system

Question 23

Why is identifying self and non-self important?

Answer 23

Allows for selective destruction of invading pathogens without destruction of host tissues
-involves major histocompatibility complex molecules (MHC)

Question 24

What are major histocompatibility complex on body cells?

Answer 24

Collection of genes that encode for self/nonself recognition potential of MHC molecules

Question 25

Where are class I MHC found?

Answer 25

On almost all types of nucleated cells

Question 26

Where are class II MHC found?

Answer 26

Only on antigen presenting cells

Question 27

Class II MHC

Answer 27

Required for T cells produce antibody communication to macrophages, dendritic cells, B cell

Question 28

Function of MHC molecules

Answer 28

Bind and present antigens to T cells to direct the adaptive immune response

Question 29

Mature dendritic cells immune response

Answer 29

Once antigen is taken up, DC becomes activated and emigrate to lymph nodes to interact with T lymphocytes via MHC class II which intimates adaptive immune response

Question 30

Where does MHC class I bind to?

Answer 30

-inside antigen/endogenous (intracellular pathogens) -MHC class I binds to antigen that originate in the cytoplasm and present antigens to CD8 + cytotoxic T cells

Question 31

Where does MHC class II bind to?

Answer 31

-outside antigen/exogenous (extracellular pathogens) -MHC class II binds to antigen fragments that come from outside the cell and present to CD4 + T helper cells

Question 32

CD4 and T helper cells

Answer 32

-recognise antigen on MHC II -help/regulate immune response through effects on B and other T cells, and phagocytes -induced to differentiate into T helper subsets by cytokines —> T helper subsets produce specific cytokines that confer function

Question 33

CD8 and cytotoxic T cells

Answer 33

-function to kill virus-infected cells -kills by direct contact - interacting with antigen - MHC class I via TCR -CD8 and T cells have cytoplasmic granules -granules contain ‘perforin’ and ‘granzymes’ -TCR/MHC class I interaction triggers degranulation

Question 34

Humoral immunity via B cells

Answer 34

-in secondary lymphoid organs and after B cell activation, plasma cells differentiate from antigen-stimulated B cells, produce immunoglobulin with identical specificity to the BCRs on its parent B cell

Question 35

What are plasma cells?

Answer 35

Antibody producing B cells

Question 36

Structure of immunoglobulin

Answer 36

-similar basic structure of Y shaped unit -each antibody consists of two identical variable regions that bind specific antigens (arms of Y) -one constant region (tail of Y that determines function)

Question 37

Different forms of antibody of immunoglobulin

Answer 37

Based on tail of antibody, five different forms of antibody Is —> IgA, IgG, IgM, IgD, IgE

Question 38

Name 1-3 of antibody

Answer 38

1.antigen-binding site 2.variable regions 3.constant region

Question 39

Antibody functions - neutralisation

Answer 39

Antibodies prevent a pathogen or toxin from binding their target

Question 40

Antibody functions - opsonisation

Answer 40

Process by which pathogens are marked via antibodies for elimination by phagocytic cells such as macrophages and neutrophils (—> and facilitate phagocytosis)

Question 41

Antibody functions - mast cell/ basophil/ eosinophil degranulation

Answer 41

By releasing inflammatory or cytoxic granules —> killing microbes (antibody-dependent cytotoxicity)

Question 42

Memory B cells

Answer 42

Maintain the ability to respond rapidly upon re-exposure -secondary immune response is quicker and much greater than a primary immune response due to memory cells

Question 43

Primary vs secondary response table

Answer 43