adaptive immunity

What is adaptive immunity’s layer of defence

3rd layer

Destroy invaders with specificity

What is A?

Physical barriers

What is B?

Innate immunity

What is C?

Adaptive immunity

What are the differences between innate and adaptive immunity?

What are characteristics of adaptive immunity?

• specificity and diversity

• Adaptation

• Memory

• Discrimination between self and non self

How is adaptive immunity’s specific and diverse?

Antigen-specific lymphocytes (T cells and B cells) carrying antigen-specific

how is adaptive immunity adaptive ?

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

What can be said about memory in adaptive immunity?

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

How does adaptive immunity discriminate between self and non self ?

Through self tolerance

What are the primary lymphoid organs ?

Thymus and bone marrow

What is the origin of lymphocyte?

Bone marrow

What’s A?

Thymus

What’s B?

Bone marrow

What’s C?

Spleen

What’s D?

Lymph nodes

What’s E?

Urogenital system

What is F?

Intestine

What is G?

Mammary glands

What’s H?

Respiratory tract

What’s I?

Salivary glands

Where are B cells from?

Bone marrow

Where are T cells from?

Thymus

What happens at the secondary lymphoid organs?

Where mature lymphocytes encounter their antigen (function)

What’s happening at A?

Start in bone marrow , immature B cell, no BCR yet

What’s happening at B?

Immature B cell , displays a BCR

Selection process , learns to ignore self-antigens

What’s happening at C?

Mature B cell leaves bone marrow to sec lymphoid organs

What’s happening at A?

T cell precursors travel from the bone marrow to develop in the thymus

What’s happening at B?

Mature T cells leave the thymus and take to secondary lymphoid tissues

Describe T cell development in thymus

Arrival in thymus - immature , no TCR

Cortex stage - acquires TCR and expresses both CD4 and CD8 (double-positive)

Selection process - learns self vs non self

Medulla stage - becomes single positive (CD4 or CD8)

Exit to secondary lymphoid organs - ready to function

What type of immunity is A?

Cell-mediated

What type of immunity is B?

Humoral

What is happening at C?

Help cytotoxic T cells and B cells in their immune functions

What’s happening at D?

Kill virus infected and damaged cells

What’s happening at E?

Produce antibodies

Fill in the gap at A

Worms, some EC bacteria, fungi

Fill in the gap at B

Phagocytosis , degranulation (Extracellular killing) , complement system

Fill in the gap at C

B cells produce antibody with help of T helper

Fill in the gap at D

Viruses, some IC bacteria, some parasites

Fill in the gap at E

NK cell killing

Fill in the gap at F

Cell killing by cytotoxic T cell

Why are different immune responses needed?

Extracellular and intracellular pathogens activate different components of the immune system

Why is distinguishing between self and non self essential?

Allows for selective destruction of invading pathogens without destruction of host tissues

Involves major histocompatibility complex (MHC) molecules

What does MHC stand for?

Major histocompatibility complex

Where are Class 1 MHC’s found?

On almost all types of nucleated cells

Where are class 2 MHC’s found?

Only on antigen presenting cells

What are Class 2 MHC’s required for?

T cell communication to macrophages , dendritic cells, B cell

What do MHC molecules do with antigens?

Bind and present antigens to T cells to direct immune response

Class 1 and class 1 MHC molecules bind to what?

Antigens

Inside antigens(/endogenous / intracellular pathogens), what do MHC class 1 molecules do?

Binds to antigens that originate in the cytoplasm and present antigen to CD8+ cytotoxic T cells

Outside antigens (/exogenous / Extracellular pathogens) what does MHC class 2 molecules do?

Binds to antigen fragments that come from outside the cell and present to CD4+ T helper cells

Which class is A?

1

What class is B?

2

What are CD4+?

T cells that recognise antigen on MHC 2

What do CD4+ T helper cells do?

Help/regulate immune response through effects on B and other T cells and phagocytes

How do CD4 differentiate into t helper subsets?

By cytokines, t helper subsets produce specific cytokines that confer function

CD4+ T cells interact with antigen and ?

MHC class 2

CD8+ T cells interact with antigen and ?

MHC class 1

What are CD8+ T cells also known as ?

Cytotoxic T cells, or cytotoxic t lymphocyte

What is the function of CD8+ cytotoxic T cells?

Function to ‘kill’ virus infected cells

How does CD8+ cytotoxic T cells ‘kill’ virus infected cells

Kill by direct intact, interacting with antigen MHC class 1 via TCR

What are some features of CD8+ T cells?

Have cytoplasmic granules

Granulates contain ‘perforin’ and ‘granzymes’

TCR/MHC class 1 interaction triggers degranulation

In secondary lymphoid organs as well as after B cell activation what happens?

Plasma cells differentiate from antigen-stimulated B cells , produce immunoglobulin (antibody) with identical specificity to the BCRs on its parent B cell

What is A?

Antigen binding site

What is B?

Variable region

What is C?

Constant region

What does each antibody consist of?

2 identical variable regions that bind specific antigens

One constant region

How do antibodies do neutralisation?

Prevent a pathogen or toxin from binding their target

Opsonisation is an antibody function, what is it ?

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

Mast cell/ basophil/eosinophil degranulation is an antibody function, how does this occur ?

By releasing inflammatory or cytotoxic granules, killing microbes (antibody-dependent cytotoxicity)

What is a memory cell?

Maintain ability to respond rapidly upon re exposure

Why is secondary immune response quicker and much greater than a primary response?

Memory cells

Humoral immunity is mainly protection against what?

Against Extracellular pathogens (or as long as they appear in Extracellular spaces)

Cell mediated immunity is mainly protection protection against what?

Intracellular pathogens (or as long as they appear in intracellular spaces)