Block C Flashcards
In the lymph nodes, what does the germinal centre contain
B cells
In the lymph nodes, what does the paracortical area contain
Mostly T cells
In the lymph nodes, what do the Medullary cords contain
Plasma cells
In the lymph nodes, what does the parafollicular area contain
An area where B cells, T cells and DCs can interact and present to each other.
Describe how T-cells undergo selection in the thymus. (3 marks)
-APC presents a immature T cell with MHC
-cells that react too strongly are negatively selected and are sent signals for apoptosis
-cells that react moderately are positively selected and recieve signals for survival
What is the main point of entry in the lymph nodes, and for T cells
the afferent lymphatic vessels, however the T cells enter through HEV
Whats is the main point of exit in the lynph nodes, and for T cells
the efferent lymphatics, T cells that are not activated leave via corticol sinuses
Describe the interaction of dentritic cells (DC) in the periphery and lymph nodes. (4 marks)
-Immature DC that are present in all tissue engulf an antigen in the periphery
-DC become activated and travel to the lymph nodes via lymphatics
-Mature DC present to B and T cells in the follicular region, activating T cells
-Once activated, T and B cells leave through the efferent lymphatics to the rest of the body
In the Spleen, what is the function of the red pulp
RBCs are broken down and produced
In the Spleen, what is the function of the white pulp
contains the region where B cells, T cells and APC are found
Why is it important for lymphocytes to continually recirulate throughout the peripheral lymphoid tissue
It ensures a lymphocyte will always find its specific antigen no matter where it enters in the body
Which MHC molecules present antigens to CD4+ T cells
MHC II
Which MHC molecules present antigens to CD8+ T cells
MHC I
Are CD4+ T cells, helper or killer cells?
helper
Are CD8+ T cells, helper or killer cells?
killer
In T cells, the _____ region recognises the antigen.
variable
Describe a T cell after activation. (2 marks)
-T cells proliferate in the lymph nodes
-T cells differentiate into effector functions and leave the lymph nodes via efferent lymphatics
Why is MHC diversity important
High diversity is needed to increase the range of peptides and reduces the chance of pathogens evading the immune system
Describe the process of a CD8+ T effector cell after activation
-once a cell has recognised the antigen via MHC I, it will recieve signals to proliferate
-these signals are sent 2 ways, through increased production of IL-2 and increased gene expression of IL-2 receptor
What the effect of IL-2 on a CD8+ cell
IL-2 binding to a receptor on the cell signals for proliferation
What the effect of IFNy on a CD8+ cell
IFNy instructs the cell to differentiate and kill pathogens
Describe the process of a CD4+ T effector cell after activation
The T helper cells interact with a B cell via BCR and MHC II. Stimulation from CD40-CD40L sends signals that induce the production of IL-4, IL-5 and IL-6. These cytokines tell the B cell to proliferate
What the effect of IL-4, IL-5 and IL-6 on a CD4+ cell
They tell the B cell that the T helper cell is interacting with to proliferate
Describe the full process of B cell activation (4 marks)
-If a BCR recognises the antigen, the B cell is activated and the antigen is engulfed. The antigen is then broken down into peptides.
-Peptides are loaded into MHC II and presented to CD4+ helper T cells.
-If the T cells also recognise the antigen, T cells will provide help to the B cell, through costimulation from CD40-CD40L and the cytokines IL-4, IL-5 and Il-6. -This stimulation allows B cells to proliferate and differentiate.
State the function of the Complement function of antibodies
activates a cascade of enzymes which punch holes in cell membranes by assembling a MAC
Which class of antibodies are in control of neutralization
IgG and IgA
Which class of antibodies are in control of complement
IgG and IgM
How are cells that react too little to self-MHC removed
Death by neglect, they dont recieve the survival signals.
Explain Central Tolerance (2 marks)
-This removes self reactive cells based on affinity
-This is through positive-negative selection
Explain Peripheral Tolerance (2 marks)
-This prevents an immune response to harmless antigens like food, good bacteria
-It does this because danger signals (PAMPs) are lacking
Approx how many cells are deleted through clonal selection
95%
If a T cell has not yet been exposed to an antigen it is classed as being?
Naive
Where do T-cell progenitors migrate to after they are developed in the bone marrow?
The thymus
Via what receptor does a helper T-cell activates B-cells?
CD40
The genetic basis of the T-cell specificity comes from?
Random selection of gene segments
MHC class II proteins mainly interact with which type of cell?
T helper cells
MHC class I and class II molecules are synthesised on what region of the cell:
-nucleus
-golgi apparatus
-ER
-ribsome
-lysosome
endoplasmic reticulum
Where do the mature T cells migrate to?
Peripheral lymphatic organs
In the adaptive phase of an immune response how long after the start of the response does activation of antigen-specific B cells occur and what is the duration of this response?
occurs within hours, lasts for days
Where do T-cells develop into fully competent T-cells?
thymus gland
The cytokines and chemokines released by _____in response to bacterial constituents initiate the process known as inflammation.
macrophages, and these release chemokines which attract cells that have chemokine receptors such as neutrophils and monocytes
Which type of T helper cell mediates IL-4
Th2 which regulates against extracellular pathogens
Which type of T helper cell mediates IFNg
Th1 which reguates against intracellular pathogens
TRUE/FALSE: The spleen and Peyer’s patches are secondary lymphoid organs involved in T-cell maturation.
false
TRUE/FALSE: the red pulp area of the spleen is where B-cells, T-cells and Antigen Presenting Cells interact.
false
T and B cells leave the lymph nodes via which ONE route?
efferent lymphatic system
Name 4 secondary lymphoid organ?
-lymph nodes
-tonsils
-spleen
-peyers patch
Which ONE immune cell interacts with B cells via CD40?
CD4+ T cell
An immune cell that recognises antigen presented in Class-I MHC is a?
CD8+ T cell
Which ONE cell generates the symptoms commonly associated with asthma?
mast cell
What does the abbreviation MHC stand for?
major histocompatibility complex
What is the process in which self-recognising immature lymphocytes are bound to self-antigens and then are destroyed to prevent autoimmune response?
clonal deletion
How many classes of MHC molecules are there?
2
Which ONE antigen requires the aid of a T-cell to induce formation of an antibody?
thymus dependant antigen
Which ONE cell type processes antigens?
dentritic cells
What is the first antibody expressed on a B cell?
IgM
The specific part of an antigen that an antibody binds to is known as:
epitope
The single most important effect of prednisolone therapy is:
reduction in nitric oxide production
TRUE/FALSE: Cytotoxic T cell are not important in protection against cancer because they are MHC Class II restricted.
false
Which antibody binds to FcγR on macrophages?
IgG
Which antibody binds to FcεR1 on mast cells?
IgE
Which T helper subset produces IL-4 and IL-5?
Th2
Which T helper subset controls extracellular bacteria?
Th17
Which T helper subset activates macrophages?
Th1
