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Flashcards in Autoimmunity Deck (31):
1

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

2

The key to autoimmunity is the ______

Loss of self tolerance

3

Immunological self tolerance

Ability to tolerate self-antigens that encompass the tissues of the body

4

Central tolerance

Immature T cells
- must pass positive and negative selection in the thymus before entering the periphery

5

Positive selection

Occurs in the thymic cortex
- immature T cell must prove that it has a TCR capable of interacting with a peptide antigen presented by MHC
- T cells that do not pass die by apoptosis

6

Negative selection

Occurs in the thymic medulla
- immature T cell must prove that it's TCR is not capable of responding to self-antigens with high affinity
- cells interact with thymic DC that contain self-proteins

7

TCRs ____ a high affinity for self-proteins pass the test

Without!

8

Maturation of B cells

Immature B cells undergo similar process to negative selection
- derive in the bone marrow, final stages occur in extramedullary locations (ex: Peyer's patches)

9

Receptor editing

Interaction of BCR with self-antigens may lead to deletion or gene rearrangements and expression of a new BCR
- if new BCR is NOT self reactive, cell maturation will continue

10

Peripheral tolerance

Occurs in peripheral lymphoid organs
- cells that escape central censorship are controlled by apoptosis and Tregs

11

Tregs

Regulatory cells that suppress immune responses of other cells

12

T cell activation

- Tc: destruction of target cell (NK and cytotoxic T cells)
- Th1: IL-2, IFN-gamma
- Thj2: IL-4, IL-5, IL-9, IL-14

13

B cell activation

Plasma cells --> antibody secretion

14

Autoimmune diseases may involve

Specific organs or multiple body systems and both humoral and cellular mechanisms of tissue damage

15

Organ specific

Immune reactions to a specific tissue antigen

16

Non-organ specific

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

17

Autoimmune diseases are more common in ____

Dogs
- less common in cats/horses
- sporadic in production animals

18

Autoimmunity causes

- genetic predisposition
- infectious diseases
- predisposing factors (age, gender, etc)
- drugs, vaccines
- environmental
- hormonal influences
- cancer

19

Primary

Absence of any identifiable trigger factor
- idiopathic
- true immune mediated disease
- diagnosis of exclusion

20

Secondary

Underlying trigger factor
- need to get rid of secondary cause to treat

21

Mononuclear phagocyte system

Removes old erythrocytes in the liver and spleen
- identifies antibodies against membrane bound antigens

22

IMHA

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

23

Primary IMHA

Predominant form
- idiopathic
- immune response to self-antigens --> antibodies cover RBC --> gets destroyed by macrophages

24

Extravascular hemolysis

Secondary
- antibodies are directed against foreign antigens located inside RBC
- end product is the same as primary = RBC destruction

25

MIcroorganisms

Infects or attaches to membrane of host cell
- cell surface expression of microbial antigen
- appropriate immune response
- non specifically destroys the host cell

26

Secondary immune-mediated disease causes

- inflammation
- infection
- neoplasia
- drugs
- tick borne infection
- post vaccination
- bee sting

27

Infectious triggers

Most significant trigger for autoimmunity
- immediately after infection or lag time
- viral infection: activation of numerous clones of B cells, or non specifically activate B cells and autoantibodies

28

Drugs and vaccines

Act as a hapten, binds to membrane of a cell to form a target of an immune response
- may modify the structure of a self-protein

29

Secondary immune mediated treatment

Treat underlying condition
- supportive care
- immunosuppressive therapy

30

Genetic predisposition

Genetic etiology is perpetuated in a population
- gene most strongly linked to autoimmunity - MHC, presenting self-antigens to auto-reactive T cells

31

Intravascular hemolysis

Antibodies AND complement coats the RBC = osmotic cell lysis