Immunology Flashcards
1
Q
what is the structure of an immunoglobulin made of?
A
Y shaped antibody in which the 3 hypervariable branches ( stem + 2 arms) bind to different copies of the same antigen
- Framework of Y composed of the variable heavy chains & the stem: crystallizable fragments composed of constant heavy chains
- Arms: hypervariable antigen binding sites made of lights chains & disulfide bonds
2
Q
what is a heavy chain and why is it important to the immunoglobulin structure?
A
it gives an antibody its family name -the framework region of heavy chains is both constant and hypervariable -types of heavy chain types include: G A M E D
3
Q
what are light chains and why are they important to the structure of an immunoglobulin?
A
antigen binding sites that finds matching antigens and attaches to it
-very specific in structure: they can only bind to the same one antigen of one bacteria/virus
»_space; Both arms - bind to same antigen of that virus
4
Q
what are the two types of systems that make up the immune system?
A
- innate immune system
2. adaptive immune system
5
Q
What is the innate immune system?
A
exists from birth and is NOT “learned”
-genetically programmed to protect us from molecular components found in microorganisms
6
Q
What are the four hallmarks of inflammation?
A
- Rubor (redness/erythema)
- Calor (heat/warmth)
- Dolor (pain)
- Tumor (swelling)
- patients will present with 2-3 out of the 4 signs
7
Q
What is the adaptive immune system?
A
“learned” by T and B lymphocytes as a result of exposure to antigens
8
Q
what are the two types of immunity?
A
- humoral immunity
2. cell-mediated immunity
9
Q
what is humoral immunity?
A
- implying the involvement of antibodies
- the protective portion of the immune system found in the plasma of the blood (humor= cell-free body fluid orserum)
10
Q
how does cell mediated immunity differ from humoral immunity?
A
cell mediated immunity response does NOT involve antibodies
-involves the activation ofphagocytes,T-lymphocytes, and often the release of various cytokinesin response to an antigen
11
Q
what is cell-mediated immunity directed primarily at?
A
- microbes that survive inphagocytesand
2. microbesthat infect non-phagocytic host cells
12
Q
which type of immunity is most effective in removing virus-infected cells?
A
cell-mediated immunity
13
Q
aside from viruses, what else does cell-mediated immunity defend against?
A
• fungi • protozoans • intracellular bacteria • cancers *also involved in transplant rejection
14
Q
what are the cellular components of the innate system?
A
phagocytes which are a group of immune cells specialized in finding/eating bacteria, viruses, dead cells
-4 types of phagocytes
15
Q
what are the 4 types of phagocytes?
A
1. granulocytes > neutrophils > eosinophils > basophils (aka mast cells) 2. Macrophages > AKA tissue monocyte 3. dendritic cells > AKA phagocytic cells (the housekeepers) 4. natural killer cells
16
Q
what are granulocytes and what is their function in the innate immune system?
A
neutrophils, eosinophils, basophils (aka mast cells)
-Attack rapidly & in large numbers (like a pawn in chess!)
17
Q
what are macrophages and what is their function in the innate immune system?
A
macrophages start out as WBC (monocytes) -> once they enter blood = macrophages
- key player in alerting the rest of the immune system to invaders
- Slow to respond in attack but have a longer lifespan, are larger and have greater capacities
18
Q
what are dendritic cells and what is their function in the innate immune system?
A
phagocytic cells that are the housekeepers which help activate the immune system
-also capable of filtering body fluids to clear them of foreign organisms & particles
19
Q
what are the Humoral Components of the Innate System?
A
- consist of things cells release into the plasma *
- Physical barriers: skin (keratin), mucous membranes (mucus)
- Cytokines (released from white cells & attract inflam cells)
- Enzymes (lysozyme)
- Inflam. mediators released by macrophages, mast cells, and NK cells
- Interferon
- complement proteins
20
Q
what is interferon and how is it important to the innate immune system?
A
chemical released by virus-infected/dying cells (inhibit viral replication)
-as an infected cell dies, it releases a chemical message that alerts other cells to keep viruses from replicating in other cells
21
Q
what are complement proteins and how are they important in the innate system?
A
roughly 20 serum protein fragments made from the liver
- interact w/ antigens
- similar to clotting cascade
- activated by inflammatory process -> augment/amplify effects of the immune system
22
Q
what effects are complement proteins responsible for?
A
- Bacterial opsonization
- Directs cell lysis
- Chemotaxis (trigger inflam)
- Attract and aid phagocytes
23
Q
what is bacterial opsonization and how does it facilitate phagocytes?
A
opsonin- any molecule like immunoglobulin & complement proteins that targets an antigen for immune response
- the opsonins bind to an antigen on the invader (antigenic invader = bacteria/virus)
- flags invader bacteria/viruses by coating them w/ complement protein
- allows phagocytes to better recognize and engulf them
24
Q
what are the cellular components of the adaptive immune system and how do they contribute to the adaptive immune response?
A
- B lymphocytes
- T lymphocytes
Lymphocytes interact w/ one another to process/retrieve data to carry out immune responses to antigenic stimuli
25
what are T lymphocytes and what is their role in the adaptive immune system?
control the adaptive immune response & produce antigen-specific cell mediated immunity with these functions:
1. Scan intracellular environment for foreign invaders
2. Directly kill virally or bacterially infected cells; also eradicate CA cells
3. Activate other immune cells
4. Remember a foreign invader they encountered decades ago (memory)
26
what are the negative effects of T cells in immune responses?
- transplant rejection
- some allergic rxn
ex) gluten intolerance
- all autoimmune diseases
ex) DM, MS, RA
27
Helper T cells (TH cells)
express CD4 surface glycoprotein on their membranes which initiate activity of:
- B cells
- macrophages
- NK cells
- cytotoxic T cells
- other T helpers
* must be activated by effector helper cell
28
Regulator T cells (Tr cells)
suppressor cells that modulate immune system by:
| -maintaining tolerance to self antigens, thus restraining autoimmune disease
29
how do regulator T cells prevent autoimmune disease?
suppression or down regulate induction & proliferation of NK cells)
30
what are antigen-presenting cells in the adaptive immune system and what is their role?
- monocyte/macrophage
- dendritic cells
activates naive helper T cell in peripheral lymphoid tissue to make them into effector helper T cells
31
TH1 effector cell
defends against intracellular pathogens by secreting interferon-gamma and tumor necrosis factor-alpha
- activate macrophages to kill microbes located w/in macrophages’ phagosomes
- activate cytotoxic T cells
- ALSO stimulate B cells to secrete specific subclasses of IgG
32
TH2 cell
defends against extracellular pathogens
-secretes interleukins, stimulate B cells to make most classes of antibodies (IgE and subclasses of IgG) -> release local mediators
33
what is the effect of local mediators released by B cells stimulated by TH2 cells?
expel extracellular microbes & parasites from epithelial surfaces
ex) sneezing, coughing, diarrhea
34
Cytotoxic T cells (TC cells)
express CD8 surface glycoprotein
| -induce apoptosis (lysis) of cells displaying epitopes of foreign antigen on their surface
35
what is an epitope?
*major key to antigen presentation:
antigen fragment from an invader which phagocytes such as dendrites display on surface to present to helper T cells
-subsequently activates helper T cells into armed effector T cells
36
what are types of cells that can be used as epitopes by cytotoxic cells?
-virus-infected cells
-cells containing intracellular bacteria/parasites
-cells exhibiting aberrant differentiation and antigens (dysplasia, neoplasia)
allogeneic cells in the process of graft rejection
37
what are the primary effects of the humoral components in the adaptive immune system?
- T cells stimulate other cells to secrete a variety of cytokines, interleukins
- Cytotoxic T cells release lytic enzymes
- B lymphocytes synthesize and release antibodies
38
lymphocytes
cellular component of lymphatic system - B & T lymphocytes
- has its own circulatory system separate from blood
- originate in bone marrow
- use T cells to migrate to lymphatic system after nmatured from bone marrow
- surface of lymphocytes individually have a specific type of receptor that matches to one specific antigen
39
what are some organs that make up the lymphatic system which T cells migrate to?
thymus
lymph nodes
spleen
40
how are helper T cells activated in the cell mediated immunity?
by antigen presentation
1. helper T cells activated by specific antigen from phagocyte displaying antigen fragment from invader on surface (epitope)
2. receptor of naive T cell recognizes antigen& becomes armed effector T cell
3. helper T cells multiply/produce proteins that activate B & killer T cells
41
what is the major driving force/main regulators of the immune defense?
Helper T cells
| -originate from thymus after maturing from bone marrow
42
Killer T Cells (Cytotoxic) in cell-mediated immunity
CD8
- Specialize in attacking cells of body infected by viruses and bacteria
- Receptors that search each cell; recognizes infected cells by epitopes
43
what make up the CD4 helper line of T cells?
```
Tн1 (intracellular pathogens)
Tн2 (extracellular pathogens)
Tregulator* (formerly: “T suppressor”)
Tн17
T(follicular) helper
```
44
what is the role of T regulator cells in relation to the rest of the T cells?
T regulator cells are essential in suppression
> full suppression in capacity of Th-1 cells
> moderate suppression of Th-2
> only early suppression of Th-17 cells
45
how are B cells activated?
1. Search for antigen matching receptors -> when binds, trigger set off inside the cell
2. Call for proteins produced by helper T cells in order to become fully activated
> Replicates to produce clones of itself
> Two new cells created: plasma cells (general antibodies) and B memory cells
3. Plasma cell produces a specific antibody that will respond to the same antigen that matched its parent B cell receptor
46
what immune response are B cells responsible for?
secondary immune response
47
what kind of globulins are antibodies?
gamma globulins
| -aka immunoglobulins
48
what are the actions of immunoglobulins?
1. Neutralize toxins and incapacitate viruses preventing from new cell infection
2. Act as opsonins (immunologic catalysts)
3. Act w/ complement to lyse certain cells
4. Agglutinate antigens
5. Degranulate mast cells (IgE)
6. Provide protection against specific antigens (IgG)
49
how do immunoglobulins incapacitate viruses?
antibodies neutralize toxins by changing the surface of viruses to make them less infectious
50
what is the process of agglutinating antigens?
antibodies grab antigens from separate places and bring them together to present them to phagocytes
51
how do immunoglobulins provide long lasting protection against specific antigens?
via the formation of immunoglobulin type G variety
52
what is an opsonin?
any molecule that targets an antigen for an immune response
53
what are the types of light chains?
kappa
| lambda
54
what are the immunoglobulin classes and what types of immunity do they play a role in?
IgG , IgM, IgA, IgE, IgD
1. active immunity
2. passive immunity
55
of the lymphocytes, which has a longer life span?
memory T cells -> produce better immune response
| - memory B cells are shorter but still remember intruders from the past
56
how are memory T cells more effective than B cells when producing an immune response?
decades after having chicken pox, any chicken pox virus that enters the body gets eradicated before you develop symptoms
57
of the lymphocytes, which memory cell plays a role in the primary immune response in the humoral system?
B lymphocyte
- primary response is slow but defends body at onset of novel infection/virus
- B lymphocyte is dedicated to producing that one specific antibody for the rest of its life in presence of particular antigen from virus -> formation of plasma cell
58
what is the most prevalent immunoglobulin circulating in blood?
IgG
- 80% circulating in blood
- monomer structure
59
why is IgG important?
it provides long-lasting immunity & is the ONLY immunoglobulin that can cross placenta
60
why is IgM important?
responsible for bloody typing (includes anti-A and anti-B antibodies)
- largest molecular structure of a pentamer = 10 antigen binding sites
- structure allows for facilitation of agglutination rxn's
61
why is IgA important?
secretory antibody found in many body fluids
ex) tears, saliva, sexual fluids, lining of respiratory and GI tracts, breast milk
- structure of IgA = dimer -> 4 antigen binding sites
62
why is IgE important?
plays a significant role in anaphylaxis
| -monomer
63
why is IgD important?
plays a role in intercellular “signaling”
| -monomer
64
what is active immunity?
humoral antibody response conferred by the body’s own response to an antigen
-stimulated by natural exposure or inoculation
65
passive immunity
conferred by the administration of exogenously created antibodies
- involves those that cross the placenta, those found in breast milk or those given IV/IM
ex) Rhogam
ex) anti rabies immunoglobulin
ex) breast milk to baby = IgG to baby
66
inoculation
planned/intentional exposure to an antigen to strengthen immunity
ex) vaccinations
67
vaccination
a form of active immunization employing inoculation
- induces a primary immune response so that the patient produces the faster and more effective, secondary response upon natural exposure to a pathogen
* slow but important for adaptive immune system
68
role of antibody exposure/vaccination in primary and secondary immune response
Incubation 10-12 weeks
1. Body makes IgM first
- IgG then starts -> makes memory cells
2. As IgG begins to rise, IgM drops off
Titers tell you whether you have had infection currently or in the past
69
why is IgM not necessary in the secondary immune response?
due to the amount of IgG providing long lasting immunity
| -memory B cells
70
what are the 3 types of disorders of the immune system?
1. Hypersensitivity / Allergy
2. Autoimmune Disease
3. Immune Deficiency
71
what is a hypersensitivity reaction?
abnormal immune response to exogenous antigens (external environment) or a reaction to endogenous auto-antigens (body's tissues)
-allergic disorders
72
what is the manifestation of a hypersensitivity reaction?
what the rash looks like
- hives / urticaria
- angioedema
- eczema
73
what is the cause of a hypersensitivity reaction?
the specific allergen which was the cause of the reaction
- food
- chemicals
- sunlight
- allergens
- microbes
74
what is the mechanism of a hypersensitivity reaction?
How the allergen creates the body's response resulting in a manifestation
- includes immune
- non-immunologic
Ex) what mechanism does ragweed have to cause rash on skin?
Nonimmunologic- not always mediated by immune system
75
what are the 4 types of hypersensitivity?
1. Anaphylactic hypersensitivity (Type I)
2. Antibody-dependent cytotoxic hypersensitivity (Type II)
3. Immune complex hypersensitivity (Type III)
4. Delayed/Cell-mediated hypersensitivity (Type IV)
76
how do you distinguish a reaction from the 4 types of hypersensitivity?
time frame of the reaction/response
77
what type of immune response is anaphylaxis and what is the cause?
secondary immune response that is life threatening and systemic
-the body was previously exposed and sensitized to allergen
78
what is the mechanism of anaphylaxis?
```
Mediated by IgE which causes the degranulation of cells
>> triggers mast cells, basophils and eosinohils to release vasoactive substances such as:
-histamine (brochoconstriction),
-prostaglandins,
-leukotrienes (mucus, lacrimation),
-cytokines (eosinophilic chemotaxis),
-bradykinin,
-serotonin (vasodilation, edema)
```
79
how does anaphylaxis manifest?
> skin - hives, eczema, angioedema
> pulm - bronchospasm, allerg. rhinitis
> cardiovas - hypotension, tachycardia
> GI - bowel edema, abd pain
80
what are some examples of anaphylaxis?
```
bee venom
IV contrast materials
foods
pollen
mold
animal dander
```
81
what are the characteristics of a true allergy?
Anaphylaxis = true allergy to have 1/4 organ systems affected
82
what are the 3 types of anaphylaxis that differ in timeframe?
1. immediate rxn -2 or more organ systems affected in seconds to minutes
2. acceleted rxn - rxn w/ involvement of skin and/or mucosal tissue + respiratory compromise or low BP or sx of end organ dysfunction in minutes to hours
3. reduced SBP > 30% from baseline any time after exposure to allergen
83
what is the mechanism of type II hypersensitivity (cytotoxic) and the cause?
1. mechanism: mediated by antibodies of the IgM or IgG classes and complement
2. cause: Triggered by endogenous antigens
* exogenous chemicals (haptens) can also cause type II
84
why do some patients experience manifestation of an allergic rxn from a transfusion?
```
cytotoxic hypersensitivity (type II)
>> IgM directed at antigens A and B on blood cells
```
85
what are some examples of type II cytotoxic hypersensitivity?
```
transfusion reactions
Rh disease (erythroblastosis fetalis)
pemphigus
autoimmune and drug induced hemolytic anemia
rheumatic fever
myasthenia gravis
Graves’ disease
Goodpasture syndrome
pernicious anemia
```
86
what is the mechanism of type III hypersensitivity?
Antibody and antigen bound together -> immune complex
>> IgG and IgM complement, mostly IgG
*** antigen is soluble & bound in blood
87
what are some examples of type III hypersensitivity?
```
*immune complex
some transfusion reactions
some insect bites
serum sickness
arthus reactions
Lupus
rheumatoid arthritis
polyarteritis nodosa
HSP
Reiter’s syndrome (reactive arthritis)
```
88
what is the mechanism of type IV hypersensitivity?
all cell mediated by T lymphocytes & dendritic cells -> release of cytotoxic T cells and macrophages
*** NO antibodies involved ***
89
what is the cause of type IV hypersensitivity?
- delayed to cell mediation
| - major mechanism of defense against the antigens of various intracellular pathogens
90
what are examples of type IV hypersensitivity?
```
Immune response to mycobacterium (TB), fungi, parasites
PPD skin test
poison ivy
photoallergic and photocontact dermatitis
morbilliform drug rashes (the continuum)
transplant rejection and GVH disease
neoplasm surveillance
sarcoidosis
Crohn's disease
```
