Immuno: Autoimmunity Breakdown Tolerance Flashcards
Definition of autoimmunity
B and T cells recognize own cells and it is a process of launching attack against their own cells
Definition of immunity
The immune system protects the body by producing antibodies and white blood cells that attack germs like viruses and bacteria
Definition of immunodeficiency
The immune system doesn’t respond properly to infections. Symptoms include slow healing, chronic fatigue, digestive issues, and allergies
Definition of hypersensitivity
An immune system overreaction to an antigen, such as a food, medication, or chemical. Hypersensitivity can cause allergies and other immune diseases.
Mechanism(s) of central tolerance
Clonal deletion
Mechanism(s) of peripheral tolerance
Anergy
Deletion
Suppression
Clonal deletion occurs during lymphocyte (t and B cells) maturation in the ______ ________ organs.
Primary lymphoid organs ( thymus and bone marrow)
Clonal deletion: The body presents immature lymphocytes with self antigen. Lymphocytes which react with _____ affinity to this self antigen are deleted.
High
Clonal deletion: Lymphocytes that are presented and react with low affinity to the self-antigen are ______ __ _____.
Selected to mature
Peripheral tolerance takes place where in the body?
Everywhere but the thymus and bone marrow
Peripheral tolerance: During maturation, lymphocytes _____ be presented with every self-antigen
Cannot
Peripheral tolerance: Lymphocytes cannot be presented with every self-antigen for what two reasons
- Some antigens are found in low concentrations in specific locations
- New antigens are formed during life
Anergy induction is the stage in which….
T cells become unresponsive to the antigen stimulation due to inadequate activation of T cells.
What is another name for B7
CD80/CD86
CTLA-4 binding B7 proteins transmits _______ signal that shuts down _____ activity
Inhibitory, T cell
When CD28 binds to B7 it provides _______ signal for T cells recognize own activation
Costimulatory
Deletion is the process
Of deleting or killing the autoreactive cells. It is also called apoptosis
Suppression is when T regulatory cells found in thymus and peripheral tissues, inhibit the functions and activation of ______ T cells
effector
Suppression:
prevents auto-reactive T cells from attacking self antigens
What are the four causes for loss of self-tolerance
- Exposure of normally inaccessible self-antigens
- Self antigen modification
- Molecular mimicry(cross reactions)
- Chronic inflammation
Exposure of normally inaccessible self-antigens: Physical trauma to one eye initiates _________ that can destroy vision in both eyes called ________ ______-
Autoimmunity, Sympathetic ophthalmia
Self Antigen modification: normal self antigens may be modified by factors such as ______,_____,and _____ ______so they no longer recognized by the immune system as a self Ag
Viruses, drugs, and genetic mutations
Molecular mimicry: infectious agents appear ______ to self-antigens
Similar
examples of molecular mimicry:
Reaction between Streptococcal Ag and myocardium in rheumatic fever
Chronic inflammation can cause significant ____ _____
Tissue damage
tissue damage due to chronic inflammation exposes/releases ____ __
Self- Ag
Chronic inflammation is linked to an increase in ___________
Autoimmunity
Where does positive selection occur?
Cortex
Thymus epithelial cells express _____
MHC
If CD8 and CD4 (as one cell) bind WEAKLY to MHC 1 and 2, it causes cell death which is a from of ____________ selection
Positive
In the medulla, CD8 and CD 4 _______ into two cells
Differentiate
What form of selection takes place in the medulla?
Negative selection
In the medulla, thymus epithelial cells and dendritic cells express______ __________.
Self antigens
In the medulla, CD 8 and CD4 (separate cells) bind strongly to self antigens resulting in cell death. This is a form of ___ selection
Negative
Maturing T cells in the medulla and cortex survive if the T cell receptor does what two things?
- Binds with self MHC1 and MHC2
- Does not bind with self antigens
How does genetics contribute to autoimmunity:
-genetic defects can cause failure of intrinsic tolerance
-Autoimmune conditions run in families
What is Hashimoto’s thyroiditis disease?
Antibodies are produced against thyroglobulin and destruction to thyroid gland’s hormone secreting capacity
Hashimoto’s thyroiditis causes
Hypothyroidism
What is Grave’s disease?
Ab stimulates inappropriate function of TSH-R causing more thyroid hormone production than normal
Grave’s disease causes
Hyperthyroidism
