Exam 4: Dr. Thomason Autoimmunity Flashcards Preview

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

Flashcards in Exam 4: Dr. Thomason Autoimmunity Deck (52):
1

What do immune mediated diseases develop from?

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

2

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

Many and varied types of diseases

3

What can disorders involve with immune-mediated diseases?

Specific organs or multiple body systems

4

What do immune mediated diseases require?

A variety of diagnostic tests and treatment options

5

What is the key to autoimmunity?

The loss of self-tolerance

6

What is immunological self-tolerance?

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

7

Describe central tolerance

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

8

What are the two tests in central tolerance?

Positive selection
Negative selection

9

Where does positive selection occur?

In the thymic cortex

10

What is positive selection?

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

11

What happens with a T cell with a functional TCR?

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

12

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

It dies by apoptosis

13

Where does negative selection occur?

In the thymic medulla

14

What is negative selection?

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

15

What do cells interact with in negative selection?

Thymic DCs that contain self proteins

16

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

They pass the test

17

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

They fail the test

18

What happens to T cells that fail negative selection?

They may potentially have auto reactive TCRs and undergo apoptosis

19

What do positive and negative selection lead to?

Marked loss of cells during intrathymic maturation

20

What do immature B cells undergo?

A process similar to negative selection

21

Where do B cells derive?

Bone marrow

22

Where do the final stages of B cell maturation occur?

Extramedullary locations (Peyer's patches)

23

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

Deletion or gene rearrangements and expression of a new BCR

24

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

Cell maturation will continue

25

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

Cell will die

26

Is immunological self-tolerance 100% effective?

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

27

What are cell that escape the central censorship controlled by?

Apoptosis
Suppression by regulatory T cells

28

What are regulatory T cells?

Regulatory cells that suppress immune responses of other cells

29

How are excessive reactions prevented?

By a "self-check" system built into immunity

30

What is autoimmunity?

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

What is involved in T cell activation?

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

32

What is involved in B cell activation?

Plasma cells that have antibody secretion

33

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

The ILs that come from it can activate plasma cells

34

Describe the spectrum of autoimmune diseases

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

35

What are organ specific autoimmune diseases?

Immune reactions to a specific tissue antigen

36

What are non-organ specific autoimmune diseases?

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

37

What are examples of organ specific immune-mediated diseases?

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

38

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

Systemic lupus erythematosus

39

What are causes of autoimmunity?

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

40

Describe primary immune-mediated diseases

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

41

Describe secondary immune-mediated diseases

Underlying trigger factor

42

How are normal canine erythrocytes removed?

Via the mononuclear phagocyte system (MPS)

43

What does the MPS identify?

Antibodies against membrane bound antigens

44

What is immune-mediated hemolytic anemia?

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

45

Describe primary IMHA

Idiopathic
No identifiable cause
Predominant form of IMHA

46

Describe microorganisms as infectious triggers

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

What are causes of secondary immune-mediated diseases?

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

48

What is the most significant trigger for autoimmunity?

Secondary immune-mediate diseases

49

What is an infectious trigger for secondary immune mediated diseases?

Viral infection

50

How does a viral infection trigger secondary-immune disease?

Activation of numerous clones of B lymphocytes
Nonspecifically activate B cells and autoantibodies

51

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

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

Describe genetic predisposition in primary immune mediated diseases

Genetic etiology is perpetuated in a population
Gene most strongly linked to autoimmunity (MHC and presenting self antigens to auto-reactive T cells)