B cells and Antibodies Flashcards
T/F: there roughly 100 million kinds of B cells in the blood?
True; only about 30 of any one kind though.
These are Y shaped proteins that attach to antigens and help identify harmful non-self things for destruction
Antibodies
something that causes the immune system to create antibodies specifically targeting that something.
Antigen
Antigen that a given B cell’s receptors recognize
Cognate Antigen
part of the antigen that the antibody recognizes and attaches
Epitope
part of the antibody that recognizes and attaches to the epitope
Paratope
Where are antibodies made?
In B cells
T/F: Antibodies have to be transcribed and translated by B cells like any other protein.
True
T/F: B cell DNA has much less variety than other cells?
False; B cell DNA has much, much more variety.
In genetic coding, three successive base pairs would be called what?
codon
In genetic coding, each three consecutive bases represent what?
one amino acid
In modular design, multiple copies of four gene segments code the antibody’s what?
heavy chain.
What is the Fc Region?
a string of gene segments
T/F: the light chain has many more gene segments to choose from.
True
T/F: Junctional Diversity limits the B cell’s ability to make different antibodies.
False; in additon to modular design, junctional diversity helps bring the B cell’s ability to make up to about 100 million different antibodies.
What are attached to the surface of B cells?
antibodies
What are the antibodies on the surface of B cells called?
B cell receptors (BCRs)
T/F: All B cells eventually find their specific match.
False; most B cells never find their cognate antigen.
What are B cells that have never encountered their cognate antigen called?
naive or virgin B cells
B cells that have been activated (found their cognate antigen) are called what?
Experienced B cells
How many signals do B cells need to be activated?
Two
What are the signals needed for B cells to be activated?
Clustering of B cell receptors and Co-stimulatory signal
What are the two parts of the Co-stimulatory signal which helps to activate B cells?
T cell dependent and T cell independent (pattern recognition)
Where are complement receptors and where are they located?
Proteins on the membrane of B cells
What is the function of a B cell’s complement receptors?
they bind to the the complement protein fragments which are bound to the antigen.
T/F: B cell’s BCRs can bind to the antigen.
True
T/F: When BCR and complement receptors are brought together on an opsonized antigen, there is a massive increase in the number of BCRs that need to be clustered to signal to the nucleus.
False; this number decreases 100-fold
What is it called when the B cell is stimulated by the antigen and a helper T cell?
T cell dependent co-stimulation
Why do some antigens heavily cluster the BCRs?
they have repeating patterns of disaccharides
When some antigens have repeating patterns and heavily cluster the BCRs, what is this considered?
T cell independent co-stimulation
What is it referred to as when the B cell and the T cell meet their respective cognate antigens?
Dual confirmation of T cell dependent co-stimulation
What is endocytosed when the B cell meets its cognate antigen?
Some of the cognate antigen
What happens to the peptide fragments of the cognate antigen during T cell dependent co-stimulation?
they are presented on MHC II’s on the surface of the B cell
What is the T cell’s cognate antigen during T cell Dependent Co-stimulation?
MHC II peptide on the B cell
What does the T cell secrete that co-stimulates B cell?
cytokines
What is it called when an antigen (mitogen) binds to B cell molecules that are not BCRs resulting in a polyclonal activation of B cells?
Un-natural T cell Co-stimulation
What type of pathogen, with highly repetitive structures, can sometimes bind to B cell molecules that are not BCRs?
parasites
When a polyclonal activation of B cells occurs, what type of cells are replicated?
B cells
Do more B cells become plasma cells or memory B cells?
plasma cells
T/F: Memory B cells are known as antibody factories.
False; plasma cells are antibody factories
T/F: one plasma cell can produce 200 antibodies per second.
False; 2000 antibodies/sec
What happens to B cells after activation and proliferation?
maturation process
What are the three parts of B cell maturation?
Somatic Hypermutation, Career Decision, and Class switching.
How does Somatic Hypermutation affect the affinity of the BCR for its cognate antigen?
It increase the affinity.
What are the “career choices” for a B cell?
Plasma cell or Memory cell
What does a B cell change during the Class Switching period of Maturation?
the class of antibody it produces
When does somatic Hypermutation occur in relation to the V, D, and J gene segments?
It occurs AFTER the gene segments have been selected
What part of the antibody is changed during Somatic Hypermutation?
the antigen binding region
B cells with BCRs having higher affinity for their cognate antigen is a result of what?
Somatic Hypermutation
How long do Plasma cells live?
only for a few days
How long do Memory B cells last?
greater than 50 years
What are the five classes antibodies fall into?
IgG, IgA, IgM, IgE, and IgD (GAMED)
What determines the class of antibody?
the constant (Fc) region of its heavy chain
What occurs when the B cells “cut and paste” different constant regions?
Class switching
What class of antibody is produced (mainly) when a naive B cell is first activated?
IgM
Which class of antibody is not considered one of the four main classes?
IgD
What are the two main functions of antibodies?
Opsonization and Neutralization of exotoxins
Which class of antibody is passed from the mother’s blood to the fetus via the placenta?
IgG
Which class of antibody is the longest lived?
IgG (3 weeks)
Serum (blood) contains more of what class of antibody than any other?
IgG
Which class of antibody guards the mucosal surfaces?
IgA
Which class of antibody coats pathogens and blocks attachment?
IgA
Which class of antibody is the most abundant in the body?
IgA
How much of normal fecal matter is rejected bacteria?
about 30%
Which class of antibody is like two IgGs clipped together (two antigen binding areas)
IgA
What is the first immunoglobulin to be made following antigen recognition?
IgM
Which class of antibody is equal in size to five IgGs?
IgM
Which class of anitbody has a half-life of about one day?
IgM
Which class of antibody is known for immoblizing the antigen?
IgM
Which class of antibody activates the Complement System (classical pathway)
IgM
Which class of antibody is made in response to allergen exposure?
IgE
Which class of antibody binds to the surface of mast cells?
IgE
What causes shock during allergen exposure?
degranulatiing mast cells
What are allergens?
antigens that can cause an allergic reaction
What type of WBCs protect against parasites?
Mast Cells
T/F: Mast cells can live for years
True
What cells phagocytize and opsonize bacteria?
Mast cells
What do mast cells store?
harsh chemistry (histamine)
Which class of antibody do mast cells bind to when fighting parasites?
IgE
T/F: Massive degranulation throughout the body can increase blood volume drastically to the point of a heart attack.
False; it can decrease it enough to cause a heart attack
How can histamine cause suffocation?
contracts the smooth muscle of the respiratory tract
What is anaphylaxis?
an acute allergic reaction
What is the opposite of anaphylaxis?
Prophylaxis
to provide protection; prevent disease; guard or prevent before hand
prophylaxis
Which class of antibody was discovered in 1964?
IgD
Which class of anitbody has an unclear function?
IgD
Which class of antibody is a lot like IgM in that B cells don’t make it until they leave the bone?
IgD
Which class of antibody is a great complement fixer and good opsonizer?
IgM
Which class of antibody causes anaphylactic shock?
IgE
Which class of antibody is secreted in milk?
IgA
What is class switching controlled by?
cytokines (T cells)
T/F: different pathogens provoke different cytokines
True
T/F: cells from different areas of the body make characteristic mixes of cytokines.
True
T/F: B cells are lymphocytes.
True
T/F: B cells have very diverse, non-specific receptors (BCRS)
False; B cells have very diverse, SPECIFIC receptors (BCRs)
What do BCRs bind to?
antigens (carbs or proteins)
Cross linking of BCRs and sometimes the presence of helper T cells is indicative of what type of activation?
Activation of naive B cells
What do activated B cells (plasma cells) make?
Antibodies
What stage of maturation helps B cells get an even better fit to the antigen?
Somatic Hypermutation
What careers are available to mature B cells?
memory cell or antibody factory (plasma cell)
