adaptive immunity Flashcards
what does the adaptive immune response consist of?
cell mediated responses and antibody (humoral) responses
what cell drives cell mediated immunity?
T cells
what does cell mediated immunity involve?
activation of macrophages, natural killer cells and antigen specific helper and cytotoxic t lymphocytes
what do B cells produce and drive?
produce antibodies and drive humoral immunity
what is immunological memory?
each pathogen is remembered by a signature T cell and or B cell receptor
describe how the kinetics of adaptive immunity arise?
arise following innate immune responses
usually >4-7 days following infection
what are the 3 main receptors in adaptive immunity?
T cell receptors
B cell receptors (immunoglobulins Ig)
major histocompatibility complex (MHC proteins)
where are T cells derived and where do they mature?
derived from bone marrow and mature in thymus
what do T cells give rise to?
cellular immunity
what do T cells recognise?
peptides present by APCs through T cell receptor
what does the diversity in T cell receptor allow?
respond to numerous antigens
T cell repertoire
what is the function of t helper cells? (CD4+)
help support other immune cells fight threat
what do cytotoxic T cells do? (CD8+)
destroy our own ells which have become infected (usually virus related)
what do regulatory T cells do?(tregs)
regulate or suppress other cells in the immune system
what do all T cells start as?
nieve t cells
what is CD8+ T cells?
co receptor that binds to MHC I
what is CD4+ T cells?
co receptor that binds to MHC II
what is CD3?
co receptor involved in activation of both CD4+ and CD8+ T cells
what are the 2 types of T cells?
a and b chains
or
g and y chains
what type of T cells are majority of T cells?
a and b chains
what is the role of y and g chain T cells?
role unknown but suggest innate function
(5%)
what are the 2 regions of the chain of T cell receptor?
constant region
variable region
what are the 3 gene segments encoded in the variable region?
v (variable)
d (diversity)
j (joining)
where are V,D and J gene segments of the variable region of the receptor found?
V = both a and b
D = b chain only
J = both a and b
how are genes rearranged? what is this driven by?
somatic recombination driven by RAG (recombinase) enzymes
how many combination are there for V(D)J gene?
3X10^11
what region has multiple antigen binding sites and can change shape?
variable region
what are pre-thymic T cells?
undifferentiated lymphocytes
what are the 2 types of selection in T cells?
positive selection and negative selection
what is positive selection in thyme education?
no recognition = apoptosis
what is negative selection in thymic education?
recognition of self antigen = apoptosis
what do T cells interact with in the thymus?
thymic cortical epithelial cells
what happens after positive and negative selection once their receptors are rearranged?
leaves the thymus and circulate in blood/lymphatics
- some reside in lymph nodes (secondary lymphoid organs)
STILL CLASSED AS NIEVE
how are T cells activated by dendritic cells?
immature dendritic cells take up and process antigen in the epidermis
then migrate to lymph node and mature en route
what can prime niece T cells?
mature dendritic cells with co stimulatory activity
what is required to activate and determine the fate of nieve T cells?
3 signals
what is the first signal in T cell priming?
activation of T cells
what is the second signal in T cell priming?
survival and clonal expansion of T cells
what is an anergy in T cell priming?
signal 1 but no signal 2
what is signal 3 in T cell priming?
differentiation into subsets of effector T cells (specifically for CD4+)
what happens in the 3rd signal in T cell priming for CD8+?
leads to effector function eg. production of enzymes for degradation
what is the main role of t helper 1 cells?
macrophage function
what are t helper 1 cells a source of?
interferon-y
what is the main function of t helper 2 cells?
supporting humoral responses and allergic reactions
what are t helper 2 cells a source of? what do these things do?
interleukin- 4,5 and 6 which instruct B cells to produce antibodies
what is the main role of t helper 17 cells?
support innate immune responses and enhances clearance of extracellular bacteria and fungi
what do t helper 17 cells produce?
interleukin-17 and 22
where are t follicular helper cells found?
secondary lymphoid organs in B cell zone
what do t follicular cells work with and what do they do?
with B cells for antibody production
what do regulatory T cells function in?
immune suppression
what do regulatory T cells release?
inhibitory cytokines
interleukin 10
what do regulatory T cells inhibit?
T cell activation and dendritic cell activation
where does the activation of CD8+ T cells arise from?
interaction between MHCL and TCR
what is the function of CD8+ T cells?
induce host cells to undergo apoptosis
what do CD8+ T cells produce?
enzymes such as granzyme/perforin
what does perforin target in CD8+ T cells?
apoptotic signalling pathways
what does T cell priming result in?
generation of different types of T cells
what does perforin facilitate?
granzyme entry into infected cell
