Lecture 4 Flashcards
What is the adaptive immune response based on?
Clonal selection
Explain clonal selection
We are born with a large number of naiive lymphocyte receptors that each have a different specificity for a pathogen
-Once a pathogen comes into contact with the correct receptor it will proliferate and differentiate into effector cells which are then cloned
Explain the difference between effector and naive cells
-Naive cells are cells who have never seen pathogen
-Effector cells are cells that are proliferated and differentiated, have an acquired function
What are the 2 effectors of Adaptive Immunity
- B cells (HUMORAL IMMUNITY)
- T cells (CELLULAR IMMUNITY)–> helpers CD4 or killers CD8
B cell function
Secrete their antigen receptor
T cell function
1.Kill infected cells directly
2. Activate other cells
True or false: T cells secrete their antigen receptor
False
T cells NEVER secrete their antigen receptor
What is humoral immunity?
Substances found in the humours (body fluids)
-B cells secrete their antibodies
Explain humoral mediated immunity
B cells
-Extracellular bacteria is targeted by secreted antibody binds to bacteria which leads to elimination of bacteria
Explain Cell-mediated immunity of Helper CD4 T cells
-Microbes in macrophage are targeted by T lymphocyte which leads to ACTIVATION OF MACROPHAGE LEADING TO MICROBIAL KILLING
Explain Cell-mediated immunity of Cytotoxic CD8 T cells
-Virus infected cell is target by T lymphocyte which leads to LYSIS OF INFECTED CELL
How do B and T cells recognize pathogens
-Through B cell receptor or T cell receptor
Explain the parts of a B cell antigen receptor
-2 light chains and 2 heavy chains
-Antigen binding site in variable region (upper part): determines specificity of receptor
-Constant region (lower part)
-Transmembrane region
Explain the parts of a B cell antibody
-2 light chains and 2 heavy chains
-variable region (upper part):
-Constant region (lower part)
-NO Transmembrane region–> so it can be secreted since antibodies are soluble
Explain parts of T cell receptor
-2 light chains
-antigen binding site in variable region
-constant region
-Transmembrane region–>(1 alpha chain, 1 beta chain)
True or false: T cell receptor do not require a transmembrane region
FALSE
-T cell receptors ALWAYS have a transmembrane region since they are NEVER secreted
What kind of cells form can B cells and T cells recognize
-B cells can recognize p[athogens in their native form
-T cells can recognize pathogens that have been process by Antigen Presenting Cells (APC)
MHC Class I is recognized by?
CD8 T cells
MHC class II is recognized by?
CD4 T cells
True or false MHC I and MHC II is present in every cell of body
False
-Only antigen presenting cells (APCs) have both MHC I AND MHC II
True or false: MHC I is present in every cell of the body
True
Which frontline defenders have both MHC I and MHC II?
Macrophages and Dendritic cells b/c they are antigen presenting cells
Name the 4 Antigen Presenting Cells
- Dendritic
- Macrophages
- Circulating mononuclear cells (monocytes)
- B cells
What links innate and adaptive immunity?
Dendritic cells
What is the functional outcome of B cell activation?
Antibody production
Antibodies bind directly to pathogen/toxin leading to
-neutralization
-opsonization
-complement deposition
What is the functional outcome of T Helper (CD4) cell activation?
Activation of other cell types
What is the functional outcome of Cytotoxic (CD8) T cell activation?
The lysis of infected cells
Where is the innate immune system?
-Tissue
-lymphoid organs
-blood
Where is the adaptive immune system?
-Lymphoid
-Organs
-Blood
-Tissue
Where is the primary (central) immune system
-Thymus and bone marrow
-Where lymphocytes are generated
Where is the secondary (peripheral) immune system?
-Spleen
-Peyers patch–>small intestine
-Large intestine
GALT
-tonsils
-lymph node
-Where mature naive lymphocytes reside and an adaptive immune response can be initiated
