Micro Chapter 16 quiz
In which of the following scenarios would you expect capping to occur?
a B-cell contacts a microbe with multiple copies of the same epitope Capping occurs wen adjacent B-cell receptors bind adjacent epitopes on a microbe. Capping is T-cell independent and leads to activation of the B-cell.
Which of the following occurs after a B-cell binds to an epitope?
clonal expansion of the activated B-cell occurs
Hundreds of closely related rhinovirus strains cause the common cold. Why is a vaccine designed to stimulate an immune response against a single rhinovirus strain unlikely to prevent most cases of a common cold?
cross-protection from a single vaccine only occurs when two antigens are identical The viral proteins found in the hundreds of rhinovirus strains are not similar. Exposing the immune system to proteins from one strain will not protect against other strains that have different proteins.
Which of the following molecules is NOT included in the immunoglobulin superfamily of proteins?
antigens
How are B-cells able to respond to millions of different antigens?
B-cells randomly rearrange immunoglobulin genes to make unique antigen-binding sites
The binding of the T-cell receptor (TCR) of a TH0 cell to an antigen-MHC complex is not enough to activate the TH0 cell. A second activation signal involves an interaction between a __________ molecule on the T-cell and a __________ molecule on the antigen-presenting cell.
CD28; B7
Which of the following cytokines must be present to continue a cell-mediated, cytotoxic T-cell response?
IL-2 (the 2nd signal in cytotoxic T-cell activation is secretion of IL-2 by helper T-cells)
Breast milk and colostrum (early breast milk) provide passive immunity to infants in the form of __________ antibodies.
IgA (IgA is secreted across mucosal surfaces and is found in tears, breast milk, and saliva. Passive immunity occurs when babies receive IgG through the placenta and IgA through breast milk)
A small fraction of self-reactive T-cells escape negative selection and become __________.
Regulatory T-cells (Treg cells)
T-cells capable of activating cytotoxic T-cells are known as __________.
TH1 cells Major function of... TH1 cells is activation of cytotoxic T-cells. Treg cells is anti-inflammatory. TH2 cells is helping B-cells. TH0 cells is differentiation into TH1 or TH2 cells.
Which of the following statements correctly describes immunogens?
all immunigens are antigens Antigens are molecules that elicit the synthesis of antibodies. All immunogens are antibodies, but not all antibodies are immunogens. Some antigens are small molecules called haptens, which must be attached to an immunogen to elicit an immune response.
If you compare isotypes found in one human to isotypes in another human, you will find slight differences in amino acids. These differences are called __________.
allotypes Allotypes are a diversity between individuals of the same species. Isotypes are an antibody diversity seen between different species. Idiotypes are the diversity seen within an individual.
Which of the following is NOT a mechanism some pathogens use to avoid an immune response?
binding nonspecifically to the outside of T-cell receptors (this would trigger a cytokine storm)
What is the first molecular signal required for TC cell activation?
binding of a T-cell receptor to an antigen-MHC I complex on an antigen-presenting cells
What event leads directly to the binding of a CD40 protein on a B-cell to a CD40 ligand on a T-cell?
binding of a T-cell receptor to an antigen-MHC II complex on a B-cell
All nucleated cells in a human body normally have...
class I MHC molecules Class I MHC molecules are found on the surface of all nucleated cells. Class II MHC molecules are found on the surface of antigen-presenting cells, "professional". MHC molecules are used to present antigen to T-cells. CD4 and CD8 are most often found on T-cells.
Patients who have functioning T-cells but dysfunctional B-cells will retain __________.
cell-mediated immunity B-cells are responsible for the production of antibodies during a humoral immunity response. The specific cells that secrete antibodies are differentiated B-cells known as plasma cells. T-cells are responsible for cell-mediated immunity.
Which of the following combinations is correctly matched?
class I MHC molecules bind intracellular antigen for presentation to CD8 T-cells (class II MHC molecules present extracellular antigen to CD4 cells)
Jamal is vaccinated against varicella, also known as chicken pox, as a young child. If he has subsequent exposure to the varicella virus as an adult, what would you expect to occur?
his titer levels of IgG would be much higher than they were after vaccination Vaccination stimulates a primary immune response. During a secondary immune response, subsequent exposure would lead to class switching from IgM production to IgG production, and IgG antibodies would be secreted at much higher levels.
Why are lipids less immunogenic than proteins?
lipids are more flexible and uniform than proteins Proteins are the strongest antigens because they form a variety of shapes, maintain tertiary structures, and are made of amino acids in different combinations. Lipids and nucleic acids tend to be weaker antigens because they are more flexible and their subunits are relatively uniform.
Which of the following is considered a "professional" antigen-presenting cell (APC)?
macrophage (includes dendritic cells, mast cells, and B-cells)
Before a cytotoxic T-cell can recognize a host cell infected by a virus, it must first become activated by...
presentation with viral peptides bound to MHC I on an antigen-presenting cell
An individual has repeated exposure to the mumps virus. Upon examination of that individual, you would expect to find that his or her memory B-cells would...
produce antibodies with higher affinity than the original B-cell that bound to the mumps virus
A cytokine storm may occur when...
super-antigens bind nonspecifically to T-cell receptors
How are T-cell receptors (TCRs) used in B-cell activation?
to help initiate heavy-chain class switching in B-cells