Adaptive immunity Flashcards
What is adaptive immunity
Specific and acquired immunity
What is the adaptive immunity response
Occurs within 4-10 days
The adaptive immune response consists of cell-mediated responses and antibody responses
T cells drive cell-mediated immunity, it involves the activation of macrophages, natural killer (NK) cells
B cells produce antibodies driving humoral immunity
Each pathogen is “remembered” by a signature T cell and/or B cell receptor = immunological memory
Does adaptive immunity produce memory cells
Yes
How long is the adaptive response
4-10 days
What arwe the steps in adaptive immunity
Infection
Transport of antigen to lymphoid organs
Recognition by naive B and T cells
Clonal expansion and differentiation to effector cells
Removal of infectious agent
What receptors are present in adaptive immunity
T cell Receptor
B cell Receptor
Major Histocompatibility Complex
Why are adaptive immune receptors highly variable
Genes encoding each allows the development of a repertoire of receptors with wide specificity
What are some pattern recognition receptors
Toll like
Dectin
NOD-like
Where are T cells derived from
Bone marrow
Where do T cells mature
Thymus
Where are T cells found
Circulate in the blood and lymph and are found in large numbers in lymphoid organs
What is diversity in the TCR known as
T cell repertoire
How is it ensured T cells only respond to foreign antigens
Checkpoints are in place
What is the TCR
T cell receptor allows recognition of peptides presented by antigen presenting cells
What are the different sub sets of T cells
T helper cells (CD4+)
Cytotoxic T cells (CD8+)
Regulatory T cells (Tregs)
What do T cells start as
Naive T cells
What are T helper cells
Function to help support other immune cells t fight threats
-Can be TH1, TH2, TH17, TFH
What are cytotoxic T cells
Destory our own cells which have become infected (usually virus-related)
What are regulatory T cells
Regulate or suppress other cells in the immune system
How are T cells differentiated
Undergo ‘programming’ to determine which subset to become - driven through the DC-T cell interactions
What does CD8+ bind to
MHC 1
What does MHC 2 bing do
CD4+
What is the purpose of CD3
It is a co-receptor involved in activation of both CD4+ and CD8+ T cells
What do most T cell receptors consist of
alpha and beta chains
What do 5% of the populations T cells consist of
y and delta chains
What are the two regions of the receptors
Constant region
Variable region
What gene segments encode the variable region of a T cell receptor
V (variable) - alpha and beta chains
D (diversity) -beta chain only
J (joining) -alpha and beta chains
What drives somatic recombination
RAG (recombinase enzymes)
How are genes rearranged
Somatic recombination
How many combinations are there for V(D)J
Approx. 3x10^11
What are pre-thymic T cells
Undifferentiated lymphocytes
What do T cells interact with in the thymus
Thymic cortical epithelial cells
What is positive selection
No recognition = apoptosis
What is negative selection
The cells that DO NOT recognise the self antigen are selected
Recognition of self antigen = apoptosis
Which T cells leave the thymus
Positively and negatively selected T cells
Where do Pre-thymic T cells undergo education
Thymus by positive and negative selection
Are educated cells naive
Yes
What are B cell receptors
Immunoglobulins e.g. antibodies
How does T cell activation occur
Results from antigen presentation by dendritic cells
Where do DCs go when they take up antigens on the skin
Lymoh nodes/draining lymphatic vessels
Where do DCs mature
En route to lymph nodes after taking up antigens