Immunology 2

Question 1

Peripheral tolerance

Answer 1

additional mechanisms in periphery (OUTside bone marrow and thymus) that help ensure self-tolerance

ie: - require B7 for T cell activation
- require CD4 T cell for B cell activation
- T reg cell (regulation)
* *most Ags require CD4 T cells for B cell activation –> CD40(L)

Question 2

Microglial cell

Answer 2

the resident macrophage of the CNS

Question 3

Multiple sclerosis

Answer 3

T cell-mediated neurodegenerative disease (autoimmune issue)
–> demyelinate CNS neurons
(Ags targeted: myelin basic protein, proteolipid protein, myelin oligodendrocyte glycoprotein)
consequence: muscle weakness, blindness, paralysis
Treatment: prevent antibody migration (alpha4 integrin blocker or FTY720)

Question 4

Rheumatoid arthritis

Answer 4

chronic autoimmune disease in synovium (joint linings);
CD4 T cells trigger cytokine release –> inflammation (esp. from INFa)
* treat w/ TNF inhibitors*
genetic: associated w/ certain MHC class II genes

Question 5

Crohn’s Disease

Answer 5

autoimmune disease, = Inflammatory Bowel Disease;
CD4 T cells target GI commensal flora –> chronic inflammation
* genetic basis: loss of function mutations in NOD2 protein*
- maybe failure to regulate”DMZ”
* treat w/ Glucocorticoids, TNFa inhibitors, alpha4 integrin blocker

Question 6

Autologous Graft

Answer 6

graft from one individual to different site on self

Question 7

Syngeneic graft

Answer 7

graft between identical twins

Question 8

Xenograft

Answer 8

graft from one species to another

ie: porcine heart valve to human

Question 9

Graft vs. host disease

Answer 9

serious disease, immune cells in graft recognize and react to the host components

Question 10

Rejection (of grafts)

Answer 10

destruction of graft organ or tissue,

mediated by antibodies and T cells of the host

Question 11

autoimmunity

Answer 11

immune responses directed against self-antigen;
mediated by autoreactive B cells and antibodies, and/or T cells

• regulated/controlled by central tolerance and Tregs

Question 12

Central tolerance

Answer 12

Main process for regulating autoimmunity,

–> delete self-specific B or T cells (in bone marrow or thymus)

Question 13

Treg Cell

Answer 13

T cell w/ moderate affinity for self-Ag,
used to suppress reaction to self-Ags
* esp. w/ up-regulation of Fox3P

Question 14

Anergy

Answer 14

perpetual non-proliferative state of T cell (no activation),
result of incomplete signals for activating T cells
(ie: only MHC or B7 but not both)

Question 15

Role of CD4 cells in autoimmunity

Answer 15

• necessary for most autoimmunity responses *
• activate macrophages –> inflammation
• help auto-reactive B and CD4 cells

Question 16

Mechanism of type I diabetes

Answer 16

autoreactive T cells selectively destroy beta cells of islets of Langerhans (which produce insulin);
* genetic factor: influenced be certain HLA II alleles*

Question 17

Humoral autoimmunity

Answer 17

result of auto-antibodies against self; causes complement activation and chronic inflammation.
bind to…
- specific receptor molecs –> inhibit OR constantly activate the R!
- transmembrane proteins
* can form complexes w/ Ag that precipitate in diff. organs

Question 18

Grave’s Disease

Answer 18

problem of auto-antibodies specific to TSH (thyroid-stimulating hormone) that ACTIVATE TSH receptors

• -> enlarged thyroid, etc.
  treatment: surgery, radioiodine and anti-thyroid drugs

Question 19

Myasthenia Gravis mech.

Answer 19

auto-antibody attack on nicotinic ACh receptors,

–> block transmission at NMJ ==> progressive weakness

Question 20

Systemic lupus erythematosus (“SLE”)

Answer 20

disease: auto-antibodies against common cell parts (ie: DNA proteins); * similar to type III hypersensitivity,
- immune complexes from dying cells -> deposited on walls of blood vessels, etc. –> activate innate immune cells via Fc Rs –> more auto-Abs

Question 21

Toll hypothesis

Answer 21

related to SLE (lupus),

–> auto-immunity (esp. w/ auto-Antibodies) may be triggered by under-methylated CpG segments, so appear microbial!

Question 22

Type I hypersensitivity rxn

Answer 22

Immediate allergic rxn mediated by IgE,
reacts to…pollen, food, venom, drugs;
1st exposure: sensitization to the allergen (innocuous Ag)
2nd exposure: triggers mast cells, basophils, eosinophils on second exposure

Question 23

Rxn to helminths

Answer 23

bc = too big for phagocytosis,
must elicit Th2 and IgE response
–> mast cells, basophils, eosinophils

Question 24

Atopy

Answer 24

= predisposition to develop IgE responses to common environmental antigens –> develop many allergies.

• -w/ genetic and environmental factors –
  env. factors: early life microbe exposure and commensal flora can predispose for Th1 response and high Treg activity

Question 25

hygiene hypothesis

Answer 25

theory that atopy is higher in US/European countries bc of lower exposure to certain infections and commensal flora

Question 26

Allergens

Answer 26

small, highly soluble molecs (Ags) that diffuse into the mucosa; - delivered transmucosally at low dose, - favors Th2 response and IgE production

Question 27

categories of food allergies

Answer 27

1. IgE-mediated (type I hypersensitivity) -- nuts, fish, etc. 2. Non-IgE mediated -- Celiac's 3. Food intolerance -- lactose intolerance 4. Idiosyncracies (unknown mech)