Immune Response Flashcards
1
Q
Describe mucosa-associated lymphoid tissue (MALT)
A
- Layer of lymphoid tissue at mucosal layers in which lymphocytes are found
- Organises response to antigens entering mucosal tissue
2
Q
What are the cellular components of the innate immune system?
A
- ANTIGEN PRESENTING CELLS - Dendritic cells/monocytes/macrophages
- GRANULOCYTES
- NK and MAST cells
3
Q
What are the two types of adaptive immunity?
A
- HUMORAL - mediated by antibodies secreted by B lymphocytes
- CELL MEDIATED - T lymphocytes activate macrophages or kill infected cells
4
Q
What immune response do intra- and extracellular pathogens induce?
A
EXTRACELLULAR - humoral
INTRACELLULAR - cell-mediated
5
Q
Describe humoral immunity. PART 1
A
- B cells formed in bone marrow
- Receptors to which antigens can attach
- Produce antibodies
6
Q
Describe humoral immunity. PART 2
A
- Antigen recognised, engulfed and digested by B cell
- Displays antigen fragments bound to MHC molecules
- Attracts T cells which secretes cytokines to help B cells multiply and form antibody-producing plasma cells or memory cells
7
Q
What are antigens?
A
- Substance triggering immune response
8
Q
Describe the two antigen properties.
A
- IMMUNOGENICITY - ability to induce immune response
- SPECIFICITY - ability to react with effector mechanisms of immune system
9
Q
What are epitopes?
A
Region of antigen interacting with antibody
10
Q
What are antibodies and what do they do?
A
- Glycoproteins produced in response to antigens
- Activate complement system
- Directly attack pathogens
- Inactivate toxins produced by bacteria
11
Q
Outline antibody structure.
A
- 2 heavy and 2 light Ig chains held by disulfide bonds
- Each chain has a variable region - attaches to specific antigen
- Constant domain - determines class and function
- FAB domain - region binds to antigens
12
Q
What is the Fc domain?
A
- Important for interaction betwen antibodies and phagocytes
- Promotes phagocytosis
13
Q
Describe IgM.
A
- Third most abundant
- Main activator of complement system
- Expressed on surface of B cells
- Produced first during primary response
14
Q
Describe IgG
A
- Most prevalent class of antibody in serum
- Expressed on surface of mature B cells
- Secreted in high quantities in secondary immune response
- Found in blood/tissue/crosses placenta from mother to fetus
- Activates complement proteins/opsonises antigens/enhancement of phagocytosis
15
Q
Define IgA
A
- Second most common human immunoglobulin
- Most common in secretions e.g saliva
- Resistant to digestion - activates complement pathway when aggregated
- Defends against toxins through body surfaces with mucous membrane
16
Q
Describe IgD
A
- Role in antigen stimulated lymphocyte differentiation
- Helps B cells mature
- Acts as B cell membrane receptor on surface of B lymphocytes
17
Q
Describe IgE
A
- Least abundant Ig in serum
- Triggers allergic reactions - bind to and activate basophils and mast cells which releases histamines in response to allergens
18
Q
Describe the B cell response in the primary immune response.
A
- Antigen attaches to BCR
- Some B cells become memory cells and some become plasma cells
- Plasma cells produce antibodies specific to antigen
- IgM produced - switched to IgG
19
Q
Describe B cell response in secondary immune response
A
- Memory B cells rapidly recognise antigen and produce antibodies with higher affinity for specific epitopes
- Greater antibody levels
