Regulation Of Immune Response Flashcards
What is tolerance of the immune system?
There is not an immune response to a specific antigen (eg self antigen)
Lymphocytes tolerate antigens that they meet in early fetal life
What are the two types of immune tolerance?
Central - self reactive lymphocytes within the thymus, bursa, or bone marrow die or alter receptor sensitivity
Peripheral- mature lymphocytes that bind self antigens are turned off or suppressed by T regulatory cells
What are the selection methods for central Tcell tolerance
Negative selection- non functional TCR undergoes apoptosis
Positive selection - ensure cells recognize self-MHC (thymic cells express proteins from many different tissues)
Where does central tolerance take place?
Thymus
Peripheral T cell tolerance can occur in response to what?
Low dose of antigen
Lack of costimulation
In peripheral Tcell tolerance prolonged antigen specific suppression leads to ___________________
Colonal anergy
Very low antigen doses or very high antigen doses can lead to __________________
Immune tolerance
Eg high dose -> immune paralysis
What are the two types of Bcell tolerance?
Central and peripheral
What is central Bcell tolerance?
VDJ rearrangement, gene conversion, somatic mutation -> leads to recognition of self antigens (55-75% of the time)
Suppress Bcell at early stages in development -> not self reactive
Peripheral Bcell tolerance can occur in response to what 4 stimuli ?
Absence of co-stimulation Repeated, exhaustive antigen stimulation Oral protein in high dose or low dose Excessive suppressor cell active Excessive T-independent antigen
An ________ immune response may lead to immunodeficiency and increased susceptibility to infection
Inadequate
An ________ immune response may lead to allergies and autoimmunity
Excessive
How does the level of antigen regulate immune response
Increased level of antigen -> immune response is prolonged
Decreased level of antigen -> immune response stops
How doe antigen presenting cells regulate the immune response?
Dependent on antigen presentation -> activation of specific cells
Langerhans -> Tcell response
Follicular DC -> Bcell response
DC1 -> Th1
DC2 -> Th2
How is the immune response regulated by immunoglobulin
Inhibitory Bcell receptor (CD32)
Cross linkage with BCR
Sends inhibitory signals into Bcells –> apoptosis
How do antibody levels regulate the immune response
High IgG –> suppress production of IgG and IgM
High IgM –> suppress production of IgM
Where are regulatory Tcells found and how are they generated?
Thymus, intestine, oral
IL-2, TGF-B and retinoic acid
Regulatory Tcells produce what suppressive cytokines
TGF-B, IL-10, IL-35
IL10 has what major effects
Suppression of :
Macrophages
TH1, TH2, and TH17 cells
NK
DC
Enhance :
Tregulatory cells
What is the function of TGF-B?
Regulate Tcell activation -> reduce proliferation
Regulate machrophage
Regulate Bcell function
