Lecture 26/27: Lymphoid Flashcards
What does CD stand for? What does it mean?
Cluster of differentiation: a particular cell type displays some cell surface marker that is useful for identification purposes
What is necrosis?
When a cell bursts and dies in an uncontrolled process
What cleans up the mess after necrosis?
Macrophages
What does necrosis cause?
An inflammatory response because the cell membrane ruptures and spills cellular contents into the milieu
What is apoptosis?
Cell suicide in a controlled process
What can induce apoptosis?
Fas ligands
What are the body’s 3 lines of defense? In order.
- Physical/biochemical barriers 2. Innate/non-specific immunity 3. Adaptative/specific immunity
Describe the body’s physical/chemical barriers. Examples?
Obstacles to prevent pathogens from gain foothold on/in body: sloughing off skin cells, acidic pH in stomach and reproductive system, flushing of urinary tract, tears, mucus, cilia, commensals (bacteria to help with digestion)
Describe the innate/non-specific immunity.
Evolutionary primitive defense mechanism
Does the innate/non-specific immunity have immunologic memory?
NOPE
When does the innate/non-specific immunity join the fight?
When a pathogen enters the body
Describe adaptive/specific immunity.
More recent evolutionary development charged with discriminating between biological components that are self and non-self
What are the 3 basic characteristics of adaptive/specific immunity that distinguish it from innate/non-specific immunity?
- Specificity 2. Diversity 3. Memory
What are the 2 mechanisms of adaptive immunity?
- Humoral: B-cell mediated 2. Cellular: T-cell mediated
How does the number of Natural Killer cells change after a surgery? When is this most severe? What does this do?
Considerably decreases in number and function Most severe 3 days post-op Makes it easier for metastatic cells to seed new locations
What is the suppression of NK cells proportional to?
The extent of the surgical intervention
Describe humoral adaptive immunity.
- Antigen presented to B lymphocyte 2. B cell surface antibody reacts with antigen 3. B cell undergoes clonal expansion 4. B cell proliferates to form 2 different cell types: plasma cells and memory B cells
What is another name for B cells?
B lymphocytes
Describe how the plasma cell created by the B cell works.
It has lots of RER to secrete soluble antibodies
For how long does the plasma cell created by the B cell survive?
Weeks - months
How can one recognize a plasma cell histologically?
Large cytoplasm filled with RER
Is the memory B cell terminally differentiated?
NOPE
Is the plasma cell terminally differentiated?
YUP
What is the purpose of the memory B cell?
Produce a rapid response if the same antigen is presented again
Do the memory B cell lose its proliferative potential?
NOPE
Where do B cells go once they are released by the bone marrow?
Lymph nodes and spleen
Where do stem cells destined to become T cells go once they are released by the bone marrow?
Thymus where they mature
What happens to the thymus as you get older?
It atrophies
Describe the structure of IGs.
2 heavy chains + 2 light chains connected by disulfide bonds
What is the purpose of the variable portions of an IG? Where are they located?
Provides a certain degree of specificity for antigens On each heavy chain and each light chain (at the tip of the Y)
Where does the variable portions of IGs come from?
Somatic recombination: 3 different exons coding for heavy and light chains shuffle in order to code for novel combinations of variable portions of the antibody
What does the DNA coding for heaving and light chains consist of?
- Variable-region exons 2. Joining-region exons 3. Diversity-region exons
What are the 5 types of IGs?
- IgG 2. IgM 3. IgA 4. IgD 5. IgE
What are the 3 functions of IgGs?
- Opsonization
- Neutralization
- Protect newborn
Which are the first antibodies to be produced in an initial immune response? Ie: which IGs constitute the primary response?
IgMs
What IG is dominant in the secondary response?
IgG
Which lag is longer: lag between exposure and primary response or lag between recurrent exposure and secondary response?
Lag between exposure and primary response
What is the function of IgAs? How come?
Protect the surface of mucosas as they resist proteolysis because tagged with a “secretory component” to protect itself from lysosomal degradation within the epithelial cell while being transcytosed through it (removed for it to become fully functional again)
What is the function of IgDs?
Receptors to antigens triggering B cell activation
What are the 2 functions of IgEs?
- Participate in allergies 2. Lyses parasitic worms
What 3 Igs are monomers?
- IgG 2. IgD 3. IgE
What Ig is a pentamere?
IgM
What Ig is a dimer with a secretory component?
IgA
Which Ig is the secretory one? Across what is it secreted?
IgA secreted across lining epithelium
Where is IgA made? Example?
Plasma cells in MALT: lining of GI tract, lungs (pleural cavity), tonsils
What do all 5 types of Igs have in common?
All have same core structure of 2 heavy and 2 light chains
What are the 5 ways in which antibodies engage pathogens?
- Agglutination 2. Opsonization 3. Neutralization 4. Cytotoxicity 5. Complement activation
Describe agglutination.
Antibody binds antigen = fewer antigens
Describe opsonization.
Antibody binds antigen = antigen marked for phagocytosis
Describe neutralization.
Antibody binds antigen = blocks their pathogenic adhesion mechanisms + inactivates their toxins
Describe cytotoxicity.
Antibody binds parasitic worms = induces macrophages and eosinophils to inondate the worm with chemical agents
What are CD8+ T cells also called?
Cytotoxic T-cells
What are CD4+ T cells also called?
Helper T-cells
How is the T cell activated?
When the T cell receptor on the surface of T cells interacts with an antigen presented on an MHC (major histocompatibility complex)
What type of T cell does MHC 1 interact with?
Cytotoxic T cells
What type of T cell does MHC 2 interact with?
Helper T cells
What is another name for cytotoxic T cells?
Cytotoxic lymphocytes
What happens when the cytotoxic T cell is presented an antigen on MHC 1?
Memory T cells and cytotoxic T cells are produced
What do cytotoxic T cells do to the virally infected cells of the body? 2 options.
- They use perforin to lyse infected cells 2. They use Fas ligand to initiate apoptosis of the infected cell
What happens when the helper T cell is presented an antigen on MHC 2?
Helper T cell activated and produces interleukins inducing B cells to become active and proliferate/differentiate