Microbiology Chapter 15

Eliminating which cell type(s) would prevent activation of all naïve lymphocytes?

Dendritic cells

All of the following cells have class II MHC receptors on their surface EXCEPT

red blood cells

Cytotoxic T cells cause death of infected cells by

releasing cytotoxins, perforins, and enzymes that destroy the cell.

The term antigenic determinant is most similar in meaning to which of the following?

Epitope

After a B cell is activated to form plasma cells, those plasma cells each produce different antibodies.

False

An epitope is larger than an antigen.

False

B lymphocytes cannot produce and secrete antibody without the assistance of helper T lymphocytes.

False

Dendritic cells can only present antigenic epitopes to T cells by loading them into MHC Class II molecules on the dendritic cell surface.

False

Label C is pointing to a CD8 protein while label D is pointing to a T-cell receptor.

False

The T cell shown in the figure is a helper T cell.

False

There are no antigens that can stimulate B cells without T cell help.

False

t is impossible to generate the diversity of immune responses needed in a typical human life span because there are only an estimated 25,000 genes in the human genome.

False

T-independent antigens will produce strong, high-affinity IgD responses from B lymphocytes.

False- These antigens typically induce B cells to produce an IgM antibody response with only mild to moderate affinity.

Removing the Peyer's patches from an animal would have which significant effect on the animal?

Greater susceptibility to intestinal pathogens.

Which of the following is the only antibody class capable of crossing the placenta?

IgG

Antigen-presenting cells release what cytokine to activate helper T cells?

Interleukin-1

When activated by antigen-presenting cells, helper T cells release what cytokine that activates B cells and cytotoxic T cells?

Interleukin-2

B cell differentiation is stimulated by

Interleukins

IgM is particularly effective in cross-linking antigens because

It is a pentameter

A norovirus-infected intestinal epithelial cell would present the peptides from the norovirus capsid on which molecule?

MHC class I

Antigenic fragments are complexed with ______ and displayed on the surface of the infected cell.

MHC class I molecules

______ with antigen fragments displayed on their surfaces are known as antigen-presenting cells (APCs).

Macrophages

Which of the following are antigen-presenting cells?

Macrophages and B cells are both APC's

Which of the following pairs is INCORRECT?

Memory cells-IgM

Which of the following statements about MHC molecules is FALSE?

NK cells identify and destroy "self" cells that lack MHC class II molecules.

Select which of the following is NOT a matching pair.

Peters patches-Skin

Helper T cells ______.

stimulate B cells and other T cells

The receptors found on the T cell in the figure are

T-cell receptors and CD8 protein

Cytotoxic T cells know that a cell is infected because

that cell has antigens from the disease-causing microbe on its surface.

If a TC encountered a TH cell infected with a virus,

the TC cell would induce apoptosis in the TH cell.

Which of the following cells can be a target for cytotoxic T cells?

Transplanted cells. Virus-infected cell. Cancer cells. ALL OF THE ANSWER CHOICES ARE CORRECT

A helper T cell must be activated before it can stimulate a B cell to produce antibody.

True

A person deficient in cytotoxic T cells may be more susceptible to developing cancer.

True

Antigen fragments are presented at the surface of macrophages along with self proteins.

True

Apoptosis occurs in infected host cells, as well as during positive and negative selection in lymphocyte development.

True

Both antigen-presenting cells and B cells have class II MHC receptors on their surface.

True

Clusters of differentiation (CD) molecules are typically found on the plasma membrane of a cell. They allow for differentiation of cells that would otherwise appear identical by microscopic analysis alone.

True

Combinatorial associations are the specific pairings of light chains with heavy chains that make up an antibody molecule, allowing for greater diversity in antibody generation.

True

Cytotoxic T cells produce cytotoxins and perforins which cause death of the infected cells.

True

If the virally infected host cell shown in the figure failed to produce MHC class II molecules, the T cell would still induce that host cell to undergo apoptosis.

True

Many different antibodies can be made against a single antigen.

True

Memory B cells are formed during the primary response so that upon secondary antigen exposure, a faster and more vigorous antibody response ensues.

True

Why is the process of gene rearrangement used in creating antibodies and T-cell receptors (TCRs) so important?

Without it, we would need a single gene for every antibody and TCR required to mount all the possible responses needed during our lives.

If your cell-mediated immune response were compromised, which of the following would happen?

You would be more susceptible to viral infections.

An antigen-presenting cell presents antigen to a helper T cell on its surface using ______.

a class II MHC molecule

One of the most important jobs of dendritic cells is

activation of T cells by breakdown of whole antigens and presentation of antigenic epitopes on MHC molecules.

Clusters of differentiation (CD) molecules are important because they

allow us to differentiate between cells that may look identical by microscopy

A child with a genetic disorder that does not allow immature B cells to develop would therefore not be able to make

antibodies

The levels of IgG in an infant go down after birth because the maternal

antibodies gradually degrade

T-cell receptors (TCRs) are only capable of recognizing and responding to

antigen epitopes presented in major histocompatibility (MHC) molecules

Helper T cells interact with target cells by recognizing

antigen-MHC protein complexes

A helper T cell becomes activated by a(n) ______.

antigen-presenting cell

Antigens

are made up of many antigenic determinants (epitopes)

Antigens

are molecules that can be recognized by B or T cells.

T cells

are responsible for cell-mediated immunity

Surface receptors on immune system cells function in ______.

cell development communication identification of self/non-self molecules ALL OF THESE CHOICES ARE CORRECT

Negative selection in B and T lymphocytes occurs when

cells bind to self antigens too strongly

T-dependent antigens

characteristically have a protein component

After repeated exposure to foreign material, innate immunity

continues to react the same way.

Helper T cells secrete ______ to stimulate the proliferation of B cells.

cytokines

During the development of both B and T cells, a process called negative selection occurs. This is necessary because it helps ensure that the cells

do not recognize "self" molecules.

Cytotoxic T cells kill target cells by

exposing them to chemicals that induce apoptosis

Helper T cells

function in both cell-mediated and humoral immunity

The adaptive immune response

involves memory of antigens from previous exposure.

Cytotoxic T cells recognize ______.

viral antigens and class I MHC molecules

The figure shows an antigen presenting cell and a lymphocyte. Cell A is the ______ while cell B is the ______.

macrophage; TH cell

Which of the following statements are TRUE? 1. Dendritic cells activate naïve helper T cells 2. Dendritic cells activate naïve B cells 3. Dendritic cells activate naïve cytotoxic T cells 4. Effector TH cells activate naïve cytotoxic T cells 5. Effector TH cells activate naïve B cells

1,3,5

CD4+ T cells 1. include helper T cells. 2. include cytotoxic T cells. 3. recognize antigen presented on MHC class I. 4. recognize antigen presented on MHC class II.

1;4

Arrange the following events in clonal selection in the correct order: 1. Helper T cells are activated. 2. Macrophages ingest antigen. 3. B cells differentiate into plasma cells and memory cells.

2,1,3

Consider the figure below. Which part accounts for antigen-binding specificity?

A

What is a self-limiting disease?

A disease that resolves with or without specific treatment.

The immune system responds more quickly to second exposure to an antigen because

memory B cells are produced during the first response.

B cells differentiate into plasma cells and ______.

memory cells

A killing mechanism used by NK cells, distinct from antibody-dependent cellular cytotoxicity, depends on recognition of

An abnormal cell that lacks MHC class I molecules on its surface

Antibodies are produced by

plasma cells

B cells differentiate into ______, which make antibodies.

plasma cells

The antibody-producing progeny of an activated B cell are called ______.

plasma cells

Antigen-presenting cells

present antigen fragments on their surface. ALL OF THE ANSWER CHOICES ARE CORRECT may be dendritic cells. may be macrophages. may be B cells.

If your humoral immune response were compromised, which of the following would happen?

Antibody production would decrease.

______ are molecules that stimulate a response in T cells and B cells.

Antigens

Choose the term that describes the method of Tc cell-mediated killing of a target cell.

Apoptosis

In addition to perforins, what else is secreted by cytotoxic T cells?

proteases (e.g. granzymes.)

The clonal selection theory states that

B cells that recognize a given epitopes multiple to form a family of identical cells.

Which of the following is a primary lymphoid organ?

Bone marrow