Immune system -slide 42 to the end Flashcards
1
Q
What are the 3 types of lymphocytes?
A
B lymphocytes
- Plasma cells => secrete antiboides
T lymphocytes
- Helper T cells => secrete cytokines
- Cytotoxic T cells => directly attack infected cells
NK cells
=> naturally killer cells
- Take care of cells that look weird…
2
Q
Helper T cells recognize antigen bound to ______ (immune cells) CD4
Whereas cytotoxic T cells recognize antigen bound to ____ (non-immune cells) CD8
A
Helper T cells => MHC II
- immune cells
Cytotoxic T cells => MHC II
- Non- immune cells
3
Q
T cells are part of ______ (specific / unspecific) immunity
A
Specific
- They make up 80? of circulating lymphocytes
4
Q
What are the main types of T cells?
A
- Cytotoxic T cells
- Helper T cells
- Suppressor T cells
- Memory T cells ( provide immunological memory )
5
Q
Describe B cells
A
- Part of specific immunity
- Make up 10-15% of circulating lymphocytes
- Differentiate (change) into plasma cells
- Plasma cells:
- Produce and secrete antibodies (immunoglobulin proteins) - Antibody-mediated immunity
- A chain of events that destroys the target compound or organism
6
Q
Describe NK cells
A
- Part of the non-specific immunity
- Also called large granular lymphocytes
- Make up 5-10% of circulating lymphocytes
- Responsible for immunological surveillance
- Attack foreign cells, virus-infected cells, and cancer cells
7
Q
Go see picture slide 46
A
Go
8
Q
What is meant, when we say lymphocytes have clones?
A
- All lymphocytes contain proteins on their cell surface capable of binding a foreign antigen
- Lymphocytes that all bind a particular antigen (the same antigen) are called CLONES
9
Q
What are the steps in an immune response?
A
- Naïve lymphocytes have not yet been stimulated
- Antigen stimulates a specific lymphocyte clone of cells that have surface receptors for the antigen
- Clonal expansion occurs as the cells multiple rapidly in response to antigenic stimulation
- Some new cells become one of three types of effector cells (plasma cells, helper T cells, cytotoxic T cells )
10
Q
Go see slide 49
A
.
11
Q
What is humoral immunity, and what cell is implicated in it?
A
B lymphocytes (B cells) are responsible for humoral immunity
- Clonal expansion of B cells results in the production of plasma cells
- Each clone of plasma cells produces a specific antigen binding protein called ANTIBODY
- Memory cells are also produced => allowing for a rapid and stronger secondary antibody response if antigen is encountered again
12
Q
What is the difference in antibody concentration after a primary and secondary immune response?
A
In a first/primary exposure to an antigen, antibody concentration is smaller for a shorter period.
After a second exposure, response by B cells => a lot of antibody for a longer period of time (go see graphs slide 52)
13
Q
What is the other name for antibodies?
A
Gamma globulin
14
Q
What are the 5 classes of anitbodies, how do they vary?
A
They vary in their Fc region
- IgG - Most common, SECONDARY RESPONSE is IgG
- IgA - Secretory form (saliva, tears, breast milk etc)
- IgE - Involved in allergic responses
- IgM- Antibodies involved in primary response
- IgD- Found on surface of B cells, role unclear
15
Q
What specific cell is involved in cell-mediated immunity? What is its role?
A
T cells (T lymphocytes)
- T cells are specialized to defend against intracellular pathogens
- Use contact-dependant signaling
- T cell receptors recognize foreign antigens only with major histocompatibility complex (MHC) proteins
- MHC proteins are found on all body cells, and they vary from one person to another
16
Q
What are Major histcocompatibility complex?
A
MHC
- Antigen-presenting molecules
- They are reason for tissue rejection
- MHC proteins help our immune system defend against intracellular pathogens and cancers
17
Q
What are the 2 classes of MHC?
A
MHC I class proteins:
- Found on all nucleated cells of the body
- Recognized by NK and cytotoxic T cells (CD8 T cells)
MHC class II proteins - Found only on antigen-presenting cells (dendritic cells, macrophages, B cells)
18
Q
What are the 2 classes of MHC?
A
MHC I class proteins:
- Found on all nucleated cells of the body
- Recognized by NK and cytotoxic T cells (CD8 T cells)
MHC class II proteins
- Found only on antigen-presenting cells (dendritic cells, macrophages, B cells)
- REcognized by helper T cells (CD4 T cells)
19
Q
Where can B cells recognize and bind to antigens?
A
Lymph, interstitial fluid and blood plasma
20
Q
What is the functional role of cytotoxic T cell?
A
- Display CD8
- Attack and destroy infected cells in 2 ways
- Release PERFORIN to create holes in infected cells
- Stimulate apoptosis (cell suicide)
21
Q
What is the functional role of Helper T cells?
A
- Secrete cytokines that influence other immune cells
- Bind to B cells, promoting differentiation to plasma cells
- Display CD4
22
Q
In a immune response to infection and antigenic challenges, INNATE system responses act _________, whereas ACQUIRED system responses act more ________, but ___________.
A
INNATE => quickly
ACQUIRED => takes longer, more slowly, but is stronger
23
Q
What are the steps in immune response to extracellular bacteria?
A
- Activity of complement system: activated by components of bacterial cell wall
- Activity of phagocytes : if uncapsulated, macrophages can begin to ingest bacteria from macrophage receptor
- Role of acquired immune response (lymphocytes)
- Initiation of repair; recruitment of platelets and proteins of coagulation cascade; once bacteria are removed, repaired by growth factors and cytokines
24
Q
What are the steps in immune response to viruses?
A
- Antibodies act as opsonin ; coating viral particles to make them better targets for APCs such as macrophages
- Macrophages that ingest viruses insert fragments of viral antigen into MHC-II molecules on membrane. Macrophages secrete cytokine (interferon production)
- Helper T cells bind to viral antigen on MHC II molecule, activated Th cells then secrete cytokines to stimulate B lymphocytes and cytotoxic T cells
- Previous exposure to the virus can create memory B lymphocytes with viral antibody on their surface. activates more memory cells and promotes development of plasma cells => antibody production
- Tc cells use viral antigen - MHC I receptors with antigen, they secrete the contents of their granules onto cell surface. Perforin molecules insert pores into host cell membrane allowing granzymes to enter, cell undergoes apoptosis
25
Go see picture on slide 64 and 66
go
26
What is hypersensitivity?
Any immune response against a foreign antigen exaggerated beyond the norm
27
Name the four types of hypersensitivity
Type I - immediate
Type II - Cytotoxic
Type III- Immune complex mediated
Type IV - Delayed or cell-mediated
28
Describe the type I (immediate) hypersensitivity
| + go see figures on slide 70-71
- LOCALIZED or systemic reaction that results from the release of inflammatory molecule in response to an antigen
- Develops within seconds or minutes following exposure to an antigen
- Commonly called ALLERGIES
- The antigens that stimulate it are called ALLERGENS
- Reaction occurs via a 2 step process:
- Sensitization upon initial exposure to an allergen
- Degranulation of sensitized cells
29
What is the role of MAST CELLS (degranulating cell) in an allergic reaction?
MAST CELL
- Distributed throughout the body in connective tiisue
- Have granules that contain inflammatory chemicals
- Degranulation releases histamine, kinins, proteases, leukotrienes, and prostaglandins
30
What is the role of BASOPHILS (degranulating cell) in an allergic reaction?
- Least numerous leukocyte in the blood
- Have granules that contain inflammatory chemicals
- Degranulates like mast cells when allergens are encountered
31
What is the role of EISINOPHILS (degranulating cell) in allergic reaction?
- Eosinophilia is the accumulation of eosinophils in blood
- Mast cell degranulation can trigger the release of eosinophils from the bone marrow
- Eosiniphils in the bloodstream can degranulate
- Release large amounts of LEUKOTRIENES
- Increases severity of a hypersensitivity response
32
Released during degranulation:
_______ causes smooth muscles contraction, increases vascular permeability, and irritation
_______ causes smooth muscle contraction, inflammation and irritation.
_______ damage tissues and activate complements
Synthesized in response to inflammation:
_______ causes slow, prolonged smooth muscle contraction, inflammation, and increased vascular permeability
_______ some contract smooth muscles, other relax it
Histamine
Kinins
Proteases
Leukotrienes
Prostaglandins
33
What are some clinical signs of LACOLIZED allergic reactions?
- Usually mild and localized
- Site of reaction depends on portal of entry
- Inhaled allergens may cause hay fever
- Small inhaled allergens may reach lungs and cause asthma
- Some allergens may cause inflammation of the skin called hives, or urticaria
34
What are some clinical signs of SYSTEMIC allergic reaction?
- Many mast cells may degranulate at once
- Release large amounts of histamine and inflammatory mediators
- ACUTE ANAPHYLAXIS and ANAPHYLACTIC SHOCK can result
- Clinical sings are those of suffocation
- Must be treated promptly with epinephrine
- Common causes include bee stings and certain foods
35
How can you prevent type I hypersensitivity?
- Identification and avoidance of allergens
- Immunotherapy
- Allergy shots
- Administration of a series of injections of dilute allergen
- Must be repeated every two or 3 years
- Not effective in treating asthma
36
What are some treatments of Type I hypersensitivity ?
- Administer drugs that counteract inflammatory mediators
- ANTIHISTAMINES neutralize histamine
- Treat asthma with a glucocorticoid and a bronchodilator
- EPINEPHRINE neutralizes many mechanisms of anaphylaxis (relaxes smooth muscles, reduces vascular permeability, used in emergency treatment of severe asthma and anaphylactic shock)
37
Give an example of Type II cytotoxic hypersensitivity and explain it
The Rh system and hemolytic disease of the newborn
- If a Rh-negative mom is carrying a Rh + fetus, antibody immune response may be initiated against the fetal cells
- In subsequent pregnancy, the fetus may be at risk for hemolytic disease
- Administration of anti-Rh immunoglobulin called RhoGAM has reduced cases of Hemolytic disease in the newborn
See figure at slide 84
38
What does type III hypersensitivity cause?
Immune Complex-Mediated Hypersensitivity
- Caused by formation of immune complexes
- Trigger release of inflammatory chemicals
- Can cause localized reactions
- Hypersensitivity pneumnonitis
- Glomerulonephritis
- Can cause systemic reactions
- Systemic lupus erythematosus (SLE)
- Rheumatoid arthritis (RA)
39
Give an example of type III hypersensitivity.
Rheumatoid arthritis (RA)
- Immune complexes deposited in the joint
- Result in release of inflammatory chemicals
- The joints begin to break down and become distorted
- Damage is progressively more severe
- Trigger not well understood
- Treated with anti-inflammatory drugs
40
Give example of common autoimmune disease in human
Grave disease
- TSH receptor on thyroid cells
Insulin-dependant diabetes mellitus
- Pancreatic beta cell antigen
Multiple sclerosis
- Myelin in CSN nerons
Myasthenia gravis
- Acetylcholine receptor of motor endplate
Rheumatoid arthritis
- Collagen
Systemic lupus erythematosus
- Intracellular nucleic acid protein complexes (antinuclear antibodies)
Guillain-Barré syndrome
- Acute inflammatory de-myelinating polyneuropathy
- Myelin in peripheral nerves
