12. Adaptive Immune System Flashcards
What cells do glandular fever virus infect
b cells in lymph nodes
What must happen for t cell to become activates
T cell receptor TCR
Must engage an abnormal cell
What happens when t cell activated
becomes larger,
more adherent
and motile and
begins to make proteins that allow it to attack it’s target cell = chromatin unravels
How come t cells have wide range of receptors
acquired a gene from virus in prehistoric times,
This gene can be rearranged into many forms to make many proteins
What is consequence of every t cell having random rearrangement of the tcr gene
3 options:
- makes something useless (need mech to ensure these dont multiply)
- makes something harmful (‘self reactive t cells’ - need to destroy these
- makes the right thing = need to multiply these
where does selection process of t cells occur
thymus gland
which glycoprotein allows intracellular proteins to be displayed on the surface of cells
major histocompatibility molecules (MHC)
structure of t cell receptor and how it helps selection process
two chains
if they cant interact = then can see it cant form a proper receptor = so cell is eliminated
what will happen to ensure the correct T cells are activated and proliferates
- Antigen presenting cells (e.g. macrophages that have englufed virally infected cells) =
encourage t cells to divide - Helper T cells = release cytokines to further help proliferation
1st step to kill an infected cell
LYCTIC REACTION
- cytotoxic t cell forms tight bond with infected cell
- injects enzymes to cause cell to apoptose
what enzymes injected during lytic reaction
- perforin = causes small pores in target cell
= granzyme and granulsyin enter = cause apoptosis - FAS = a signalling protein = instruct cells to enter apoptosis
qhy apoptosis the preferred method to kill cell
Programmed cell death (apoptosis) causes cells to activate enzymes that break down all internal components including any virus preventing further spread
some wider functions of t cells
- support antibody formation
- interact w innate immune system (can be activated by DAMPS and PAMPS)
- negative regulation of immune responses
what happens when b lymphocytes are activvated
when something is recognised by the B cell receptor
= develop into plasma cell (the antibody secreting form of a b cell)
where are plasma cells found
in bone marrow
only antibodies produced are sent into circulation
what is vdj recombonation
variable region
diversity region
joining region
how are antibodies diff to T cells in terms of variability
seoncd wave variability ocurs after encountering the antigen = somatic hypermutation
THEN
undergo affinity maturation in lymph node = the good ones become dominant antibodies
treatment of inherited B or T cell deficiency
can lead to fatal infection in early infancy
so need protection in early life
then bone marrow transplant
3 ways that immune deficiency can be acquired
- HIV/AIDS infection
- immunosuppressive therapy after organ translpant
- or immunosuppression to treat autoimmune disease
how could EBV virus be reactivated
after immunosuppressant therapy given
the virus usually latent
= could even lead to EBV associated lymphoproliferative disorders - cancer
rheumatoid arthiritis
T an B cells reacting abnormally to proteins that line the membrane of joints
recruits neutrophils
bad bad
but can be treated with immuno suppressive treatment
