Regulation of lymphocyte response Flashcards
(27 cards)
Why is immune regulation needed?
For preventing
excessive lymphocyte activation and tissue damage
- inapproproaite actions agaisnt self
What are the three failures as a result of improper immune regulation?
Autoimmunity
Allergy
Hypercytokinemia and spesis
What is autoimmunity?
When lymphocytes cannot distinguish between self and non-self cells and as a result attacks its own cells
Either systemic or organ-specific
inappropriate control of imm system - keeps going
What is allergy?
Harmful imm response to benign antigens causing tissue damage and disease
Improper IgE - anaphylacitc shock
T cells - DTH
What is hypercytokinemia and sepsis
Too much immune response - positve feedback loop
Pathogens enter wrong compartment
What is the cardinal feature of immune responses?
Self-limitation
mainfested by decline in imm rep
in improper response, antigen recog ios messed up
How are immune responses controlled?
PAthogenic responses decline as infection eliminated
- apoptosis of lymphocytes lacking antigen - survival signal
Active control mechanisms limit response to persistent antigen
- tumor :( - THIS IS TOLERANCE
What is immunological tolerance?
Specific unresponsiveness to an antigen as a result of prolonged exposure to lymphocytes
Give examples of cells that we are tolerant to
Self antigens - breakdown of this leads to autoimmunity
What are the two types of tolerance?
Central
- destroy self reactive lympocytes before they enter circ
Peripheral
- destroy any lymphocytes that do enter
How is central tolerance carried out?
Apoptosed
Receptors changed
Form Treg
How is peripheral tolerance done?
Anergy
Ignorance
Apoptosis - antigen induced cell death
Suppression
Describe central tolerance of B cells
If shows to crossslink IgM w antigen, apoptosed
Describe tolerance of T cells
Depends on MHC binding, if too weak or too tight they are apoptosed - signalling is wrong and causes it to work incorrectly
What is anergy?
Absence of co-stimulatory signals that cause lower chance of stimulation even if costimulated later
What is ignorance?
[Antigen] not high enough to trigger TCR
What is AG induced cell death?
Activation through TCR
Influenced bynature of t cell actiavation - if faulty then get killed
Fas-FasL induction
What is regulation?
Peripheral tolerance
T helper cells that are regulatrory inhibit other T cells
What is IPEX
Syndrome as a result of mutation in FoxP3 that Treg has, leading to small size etc
What are the types of Treg?
natural T reg
- Thymic development, requires self antigenic recognition
Inducible T reg
- Develop from mature CD4 T cells post antigen exposure
What might occur in pregancy if irregular regulation?
Pregnancy terminated as parasitic infection
- New antigen is non-self
CELL PATHOLOGY
Distinigush between repair and reolution
Repair is loss of cuntion due to laying of collagen
Resolution is restoring original function and no damage of tissue
How may a lack of tolerance be induced?
Expousre + inflammation in wrong places
Cross reacting - sepsis
A lack of tolerance means…
That now lymphocytes can be activated and act on self or improperly
