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Immunology - DVM year 1 > Exam 4: Dr. Thomason Autoimmunity > Flashcards

Exam 4: Dr. Thomason Autoimmunity Flashcards

1
Q

What do immune mediated diseases develop from?

A

An inappropriate immune system response against cells and tissues normally present in the body

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2
Q

What can inappropriate immune responses to self-antigens lead to?

A

Many and varied types of diseases

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3
Q

What can disorders involve with immune-mediated diseases?

A

Specific organs or multiple body systems

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4
Q

What do immune mediated diseases require?

A

A variety of diagnostic tests and treatment options

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5
Q

What is the key to autoimmunity?

A

The loss of self-tolerance

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6
Q

What is immunological self-tolerance?

A

Ability to tolerate self-antigens that encompass the tissues of the body
Potentially auto-reactive T and B lymphocytes met be brought under control

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7
Q

Describe central tolerance

A

Immature T cells
Must pass 2 tests before exiting the thymus and enter the periphery
Additional safe guards in the periphery

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8
Q

What are the two tests in central tolerance?

A

Positive selection

Negative selection

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9
Q

Where does positive selection occur?

A

In the thymic cortex

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10
Q

What is positive selection?

A

Immature T cell must prove that it has created a TCR capable of interacting with a peptide antigen presented to that T cell by an MHC molecule

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11
Q

What happens with a T cell with a functional TCR?

A

It passes the test of positive selection and progresses to negative selection

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12
Q

What happens if a T cell does not pass positive selection?

A

It dies by apoptosis

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13
Q

Where does negative selection occur?

A

In the thymic medulla

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14
Q

What is negative selection?

A

Immature T cell must prove that it’s TCR is not capable of responding to these self-antigens with high affinity

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15
Q

What do cells interact with in negative selection?

A

Thymic DCs that contain self proteins

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16
Q

What happens to TCRs on cells without a high affinity for self-proteins in negative selection?

A

They pass the test

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17
Q

What happens to TCRs on cells with a high affinity for self-proteins in negative selection?

A

They fail the test

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18
Q

What happens to T cells that fail negative selection?

A

They may potentially have auto reactive TCRs and undergo apoptosis

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19
Q

What do positive and negative selection lead to?

A

Marked loss of cells during intrathymic maturation

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20
Q

What do immature B cells undergo?

A

A process similar to negative selection

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21
Q

Where do B cells derive?

A

Bone marrow

22
Q

Where do the final stages of B cell maturation occur?

A

Extramedullary locations (Peyer’s patches)

23
Q

What can interaction of the BCR with self-antigens lead to in receptor editing during B cell maturation?

A

Deletion or gene rearrangements and expression of a new BCR

24
Q

In receptor editing, what will happen if the new BCR is not self-reactive?

A

Cell maturation will continue

25
Q

In receptor editing, what will happen if the new BCR is self-reactive?

A

Cell will die

26
Q

Is immunological self-tolerance 100% effective?

A

No, some auto-reactive T cells escape clonal deletion and enter peripheral circulation

27
Q

What are cell that escape the central censorship controlled by?

A

Apoptosis

Suppression by regulatory T cells

28
Q

What are regulatory T cells?

A

Regulatory cells that suppress immune responses of other cells

29
Q

How are excessive reactions prevented?

A

By a “self-check” system built into immunity

30
Q

What is autoimmunity?

A

Failure of self-tolerance to eliminate self-reactive T and B lymphocytes into circulation
Presentation of an auto-antigen by APC allowing excessive activation of T cells

31
Q

What is involved in T cell activation?

A

Tc: Destruction of target cell (NK cells and cytotoxic T cells)
Th1: IL-2 and IFN-γ
Th2: IL-4, 5, 9, 14

32
Q

What is involved in B cell activation?

A

Plasma cells that have antibody secretion

33
Q

How does the activation of Th2 cells contribute to B cell activation and plasma cells?

A

The ILs that come from it can activate plasma cells

34
Q

Describe the spectrum of autoimmune diseases

A

Many and varied immune-mediated diseases
May involve a specific organ or multiple body systems
Both humoral and cellular mechanisms of tissue damage

35
Q

What are organ specific autoimmune diseases?

A

Immune reactions to a specific tissue antigen

36
Q

What are non-organ specific autoimmune diseases?

A

Immune response to dispersed antigens which leads to systemic deposition of immune complexes

37
Q

What are examples of organ specific immune-mediated diseases?

A 
Immune-mediated neutropenia, thrombocytopenia, and hemolytic anemia 
Myasthenia gravis
Non-erosive polyarthritis
rheumatoid arthritis
Discoid lupus erythematosus
38
Q

What is an example of non-organ specific immune-mediated diseases?

A

Systemic lupus erythematosus

39
Q

What are causes of autoimmunity?

A 
Genetic predisposition
Infectious diseases
Predisposing factors (age, gender, lifestyle, diet)
Drugs and vaccines
Environmental
Hormonal influences
Cancer
40
Q

Describe primary immune-mediated diseases

A

Absence of any identifiable trigger factor
True immune mediated disease
Diagnosis of exclusion

41
Q

Describe secondary immune-mediated diseases

A

Underlying trigger factor

42
Q

How are normal canine erythrocytes removed?

A

Via the mononuclear phagocyte system (MPS)

43
Q

What does the MPS identify?

A

Antibodies against membrane bound antigens

44
Q

What is immune-mediated hemolytic anemia?

A

Premature destruction of erythrocytes
Immune response directly/indirectly targets RBCs
Anti-RBC antibodies bind to RBC membrane

45
Q

Describe primary IMHA

A

Idiopathic
No identifiable cause
Predominant form of IMHA

46
Q

Describe microorganisms as infectious triggers

A

Infects or attach to the membrane of a host cell
Cell surface expression of the microbial antigen
Appropriate immune response
Nonspecifically destroys the host cell

47
Q

What are causes of secondary immune-mediated diseases?

A 
Inflammation
Infection
Neoplasia
Drugs
Tick borne infection
Post-vaccination
Bee-sting envenomation
48
Q

What is the most significant trigger for autoimmunity?

A

Secondary immune-mediate diseases

49
Q

What is an infectious trigger for secondary immune mediated diseases?

A

Viral infection

50
Q

How does a viral infection trigger secondary-immune disease?

A

Activation of numerous clones of B lymphocytes

Nonspecifically activate B cells and autoantibodies

51
Q

What do drugs and vaccines do to caue a secondary immune mediated diseases?

A

Acts as a happen, binds to the membrane of a cell to form a target of an immune response
May modify the structure of a protein

52
Q

Describe genetic predisposition in primary immune mediated diseases

A

Genetic etiology is perpetuated in a population

Gene most strongly linked to autoimmunity (MHC and presenting self antigens to auto-reactive T cells)

Immunology - DVM year 1 (35 decks)

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