Lecture 5 Flashcards
What do lymphocytes do?
Continuously circle through secondary lymphoid organs until selected by antigen when there is an infection
Lymph
Plasma leaked from blood into tissues
Lymphoid organs
Contains & circulates lymphocytes
What do secondary lymphoid organs do ?
Provide a meeting place for cells of the adaptive immune response
-Increases chances for lymphocytes to interact w/ correct antigen
What and how links innate and adaptive immunity
Dendritic cells
-makes cytokines (innate)
-uptakes antigen (secondary)
Which secondary lymphoid tissue deals with pathogens that make it to the blood?
Spleen
What is the difference between how pathogens and lymphocytes enter lymph nodes and spleen
-Lymph nodes enter through the lymphatic system
-enter through blood
What is the secondary lymphoid tissue is a specialized immune system in our digestive tract
GALT
How does the GALT differ from the spleen and lymph nodes?
- Can directly deliver across mucosa
- Lymphocytes stay within mucosal system
How do we produce an infinite variety of antibodies?
B cells have unique antibody receptor
-clonal selected–>proliferated & differentiated
What are plasma cells?
Effector B cells that secrete large volumes of antibodies
How many antigen binding sites do B cell receptors have?
2
How many heavy chains and constant regions are in BCRs
-2 heavy chains
-5 regions
How many light chains
-2 light chains
What happens in the variable region?
-Recognizes antigen/binding
-specificity
What happens in the constant region?
-Biological activity
-change in isotype
What is the Fab region?
Part of antibody that contains antigen binding site
(upper)
What is the Fc region?
Part of antibody that has biological activity
-binding to specific Fc receptors and complement proteins
What does the Fc and Fc receptor facilitate?
Antibody mediated opsonization
-neutralization
-opsonization
-complement deposition
What are hypervariable loops (CDRs)
Regions of the antibody that come into contact with the antigen
-forms binding pocket for antigen–>hypervariable region
Which CDR has the highest variability? CDR1 CDR2 or CDR3
CDR3 b/c it has 2 imprecise junctions
What is an epitope
Part of antigen that is recognized by an antibody that is accessible
What is a difference between what BCR and TCR can recognize?
-BCR can recognize all types of chemical structures (proteins, carbohydrates etc)
-TCR can only recognize peptides made from proteins
What are the 5 isotypes of antibodies?
- IgG
- IgM
- IgD
- IgA
- IgE
What are Ig isotypes?
Genetic variations/differences in the heavy chain constant region
What is isotype switching and what does it require?
Changes B cell production of antibody from one isotype to another
(switches isotype)
-requires help from T cell (Tfh)
True or false: Isotype switching can change the isotype of both heavy chain and light chain
False
-Isotype switching changes the isotype of the heavy chain but not light chain
-Heavy chain changes biological activity
IgM
First one to be made in immune response
-does not need T cell help (no isotype switching needed)
-Low binding affinity
-needs multiple binding sites due to low binding affinity–>becomes Pentameric (adds more binding sites)
-Ideal for complement activation b/c pentameric
What is affinity?
strength of 1 antibody binding site
What is avidity?
combined strength of multiple antibody binding sites
What antibody isotypes are used in primary response?
IgM–>early, low affinity
IgG–>late, high affinity
Which antibody isotype is ideal for complement activation
IgM due to its pentameric shape
Which antibody isotype is key for vaccinations to work and how?
-IgG
-produces neutralizing antibodies
IgA
-monomeric in serum–>good for extravasation
-can cross epithelial mucosal surfaces (dimeric)
-high in breast milk
-neutralizing antibody
IgE
-less concentrated
-shortest half life when soluble -Long life when bound to Fc receptor
-can bind to Fc receptor w/out antigen
-makes histamines/causes allergies
-fights parasite infections
What is IgE important for?
Control of parasites
Which isotype antibody causes allergies?
IgE
IgD
-expressed on surface of naive MATURE B cells
-Membrane bound not secreted as antibody
IgG
-most abundant isotype in circulation
-Monomeric
-useful for vaccines
-can be transported across placenta
