Chapter 24.

Which of these types of immunity includes the other two types?

Adaptive immunity. -These three types of immunity are very related to each other. Humoral immunity and cell-mediated immunity are both part of a person's adaptive immunity. Therefore, adaptive immunity is a broader term that includes these other two types of immunity.

Helper T Cells..

Bind only to antigens attached to MHC surface proteins on APCs.

Cytotoxic T Cells...

Bind viral antigens present on any virus-infected cell.

Which of the following statements about herd immunity is correct?

Herd immunity will not protect against an unvaccinated person acquiring a deadly disease from a sick person. -Herd immunity limits the spread of both viral and bacterial illnesses. However, herd immunity will not protect an unvaccinated individual during the actual step of disease transmission when in the presence of a sick individual. Herd immunity simply decreases the number of sick individuals. Relying solely on herd immunity is therefore not a good way to ensure that you will not become ill. Vaccination, according to CDC guidelines, is a good way to prevent illness. Herd immunity also will not provide limited protection against tetanus regardless of many people having the DTaP vaccine.

Match the cells to their immunities: I. B Cells II. T Cells

I. Adaptive immunity II. Adaptive immunity -Humans rely on both innate and adaptive immunity to protect us from colonization by foreign cells. B cells and T cells are part of a person's adaptive immunity. These cells respond to foreign particles within the body and facilitate immunomemory. Innate immunity is present from birth, and is part of our natural, nonspecific immunity against invasion by anything foreign. B cells and T cells are not considered to be part of innate immunity.

IgA

Is not produced by a fetus and most commonly is found as a dimer, explaining why it can bind four molecules of antigen (each monomer can bind two).

Her immunity is in place when _______ of the individuals within a population are vaccinated.

Most. -Herd immunity is in place when most of the individuals within a population are vaccinated. For infections spread by person-to-person contact, the risk of disease to an unvaccinated person can be lowered dramatically even when only about two-thirds of the community are vaccinated.

What does the term "immunogenicity" refer to?

The effectiveness with which an antigen elicits an immune response. -Immunogenicity refers the effectiveness with which an antigen elicits an immune response. One antigen can be more immunogenic than another. The level of immunogenicity all depends on how the target molecule interacts with cells of the immune system. Thus, immunogenicity involves an interaction between host cells and some foreign substance. The rate at which invading bacterial cells divide and cause disease, the culmination of the various signs and symptoms of disease, and the time required for one human to transmit disease to another are not the best definitions of immunogenicity.

IgG

The simplest and most abundant antibody in blood and tissue fluids. It is transmitted across the placenta. Has four subclasses.

True or false: More than one type of major histocompatibility complex proteins is integral to T-cell physiology.

True.

True or false: T cells are activated only by antigen bound to another cell's surface.

True.

True or false: T cells never bind to free-floating antigen.

True.

Which of the following is correct regarding vaccines and human health?

Vaccines may initially elicit a fever and mild infection. -Vaccines may initially elicit a fever and mild infection. The vast majority of people who receive vaccines suffer no, or only mild, reactions, such as fever or soreness at the injection site. Very rarely do more serious side effects, such as allergic reactions, occur. Vaccination has never been scientifically linked to autism or diabetes. Such claims have been purported but have been quickly debunked. The risks, including death, associated with these preventable infectious diseases are far greater than the minimal risk associated with being vaccinated against them.

________ immunity is acquired over time as the individual is exposed to various different types of foreign substances.

Adaptive. -Adaptive immunity is acquired over time as the individual is exposed to various different types of foreign substances. These foreign substances are recognized as foreign by cells that comprise the adaptive immune response. Innate immunity is present from birth, and is part of our natural, nonspecific immunity against invasion by anything foreign.

Which of the following cells would not be considered a common type of phagocytic antigen-presenting cell?

B cells. -Any phagocytic cell that degrades large antigens into smaller antigenic determinants and places those determinants on their cell surface is called an antigen-presenting cell (APC). B cells do not do this and therefore are not considered a type of APC. On the other hand, macrophages, mast cells, and dendritic cells can be APCs.

Which cell type is best associated with humoral immunity?

B cells. -B cells, and the antibodies that they produce, comprise a person's humoral immunity. T cells, macrophages, and platelets, which are all bloodborne, but do not produce antibodies and are not considered to be part of humoral immunity.

Which of the following contains a plasma membrane receptor protein that interacts with antigen?

Both B cells and T cells. -Both B cells and T cells contain a plasma membrane receptor protein that interacts with antigen. Antigen interacts with a membrane protein on the surface of these cells. Without this, the immunobiology of these cells would be completely lost. In a crucial step of antigen recognition, an activated T cell links to and activates a B cell bound to the same antigen. The B cell is then stimulated to generate a plasma cell that secretes antibody against the antigen.

The first cells likely to encounter a pathogen, such as phagocytes, are professional antigen presenting cells (APCs). This means they...

Can activate cells of the adaptive immune system. -Phagocytes present pieces of the pathogen to cells in the lymph nodes, specifically to T cells that will in turn activate additional adaptive immune system cells.

Herd immunity reduces risk for all but which of the following kinds of disease?

Diseases that do not require person to person contact. -Herd immunity reduces the risk of transmission from an infected individual to a susceptible one as there are fewer susceptible individuals present, but this only applies if the disease is spread through person to person contact. This can be direct, where there must be an exchange of fluids or touch or through indirect means, including accidental transmission. Other diseases caused by means that do not require an infected person to be involved are not protected against by herd immunity.

Identify the variable and non-variable regions within the antibody.

Each antibody has one non-variable region, at the stem of the characteristic Y-shaped representation, and variable regions, both at the arms of the representation.

Which best describes antibody structure and function?

Each antibody has two variable regions that are both specific to the same antigen. -Each antibody has two variable regions that are both specific to the same antigen. Both heavy chains are derived from the same gene, and are thus identical, and both light chains are derived from the same gene, and are thus identical. An antibody is a longitudinal mirror-image of itself, making both antigen-binding sites identical.

Which type(s) of immunity include(s) cells that are involved in the immune response to a specific antigenic epitope?

Humoral. Cell-mediated. Adaptive. -Adaptive immunity includes the cells of humoral immunity and cell-mediated immunity. Together, these cell types contribute to an individual building, and developing, immunity over time. Innate immunity is not built over time, and is naturally in place from birth.

What type of immunoglobulin is shown below?

IgA -IgA is a dimer held together by the secretory piece and J chain. The other immunoglobulins have different structures.

Suppose an individual has impaired histamine release from mast cells. This individual may have lower levels of which antibody class?

IgE. -Only IgE is involved in histamine release from mast cells.

What type of antibody is represented by the image?

IgM. -Circulating IgM is a huge, Ferris wheel-shaped molecule formed from five monomeric immunoglobulins tethered together by the J-chain protein, shown in purple. IgG, IgA, IgD, and IgE do not form pentamers. This pentameric oligomerization is specific to IgM.

The primary antibody response differs from the secondary antibody response in that...

In the primary response, plasma cells differentiate from naive B cells, whereas in the secondary response, plasma cells may differentiate from memory B cells. -Both antibody responses are triggered by exposure to an antigen. In the primary response, plasma cells differentiate from naive B cells, whereas in the secondary response, plasma cells may differentiate from memory B cells, leading to a more rapid appearance of circulating antibodies. During the secondary response, mechanisms increase the antibody affinity for an antigen.

Herd immunity protection __________ as more individuals are vaccinated.

Increases. -As more individuals are vaccinated, herd immunity protection increases. Vaccinating a large percentage of a community effectively conveys community (or herd) immunity by interrupting transmission of the disease. If one individual contracts the disease, the chance that he or she will come into contact with another unvaccinated person and transmit the disease is greatly reduced.

IgD

Is a monomer that can neither bind complement nor cross the placenta. These molecules, however, are abundant on the surface of B cells. Attached to B-cell surfaces by Fc regions, these antibodies, along with monomeric IgM, can bind antigen and signal B cells to differentiate and make antibody.

IgE

Like IgD, these antibodies are also present in only trace amounts in the blood, and is found more prominently bound to the surfaces of mast cells and basophils, where it has potent biological activity. Once secreted into serum, these antibodies attach to mast cells.

Which cell surface protein is expressed in all nucleated cells?

MHC I. -MHC I is present in all nucleated cells, but CD4, CD8, and MCH II are not. CD4 is on helper T cells, CD8 is on cytotoxic T cells, and MHC II is found on certain antigen-presenting cells.

Which describes why the secondary immune response is much quicker and greater than the primary response to the same antigen?

Memory B cells are in place when the same antigen is encountered again. -The secondary immune response is much quicker and greater than the primary response because memory B cells are already in place when the same antigen is encountered again. Once stimulated, memory B cells rapidly differentiate into plasma cells and secrete antibody. Plasma cells are much larger than B cells because of an enormous increase in protein synthesis and secretion machinery. A subsequent exposure to the antigen, which can take place months or years after the initial encounter, will trigger a rapid, almost instantaneous increase in the production of antibodies. This quick response occurs thanks to the memory B cells forming during the primary response.

Rank the following terms from largest size to smallest size: antigen, pathogen, epitope.

Pathogen, antigen, epitope. -A pathogen can contain many antigens and each antigen can contain several different epitopes.

Neither Helper T Cells nor Cytotoxic T Cells...

Produce antibodies directly.

Which is true of the adaptive immune response?

T cells can directly kill infected host cells but B cells cannot directly kill cells. -B cells, which differentiate into antibody-producing plasma cells, mediate humoral immunity. A clonal population of plasma cells will all secrete the same antibody, which will recognize a particular epitope. T cells, which can directly kill infected host cells, mediate cellular immunity.

A child was exposed to a disease-causing virus (most likely chicken pox from the Varicella zoster virus) when he was 5 years old. At 12 years old, the child encounters the same virus again. What is most likely expected to happen?

The pathogen will be neutralized with antibody quickly and the virus will be cleared before symptoms develop. -This is the description of a secondary immune response. The lag phase of antibody production occurs during the primary immune response, which would have taken place when the child was first exposed to the virus. Because the disease-causing pathogen is a virus, antibiotics will not be effective against this noncellular agent. Macrophages are also active in the innate immune system and therefore do not increase their immunoactivity based on multiple exposures to the same antigen.

IgM

Cannot transmit across the placenta and can have up to ten antigen-binding sites. This type of immunoglobulin is the only that is produced by a developing fetus.

In a process called __________, an invading antigen binds to a B cell and that B cell then proliferates to large numbers and differentiates into antibody-producing plasma cells or memory B cells.

Clonal selection. -Clonal selection is a process by which an invading antigen binds to a B cell and that B cell then proliferates to large numbers and differentiates into antibody-producing plasma cells or memory B cells. This proliferation, referred to as clonal expansion, is integral to the production of antibody that is specific to the antigen that initially stimulated the B cell. Opsonization, antigen presentation, and denaturation are not the best terms that define the interaction between B cells and antigen and the subsequent physiology that ensues.

If a patient has been diagnosed with human immunodeficiency virus (HIV), then part of their _________ immunity is not functioning properly.

Innate and adaptive. -When a patient has been diagnosed with HIV, various cells of the innate and adaptive immune systems are not functioning properly. This causes significant immune system complications in that individual, and deadly complications can happen after exposure to what would normally be non-lethal antigen. Specifically, the cells infected with HIV are T cells, macrophages, and dendritic cells.

The classical complement pathway differs from the alternative complement pathway in that

The classical pathway is activated by antigen-antibody interactions; the alternative pathway is activated by bacterial lipopolysaccharides. -The classical complement pathway and the alternative complement pathway are separate pathways that differ in how they are initially activated. The classical pathway is activated by antigen-antibody interactions; the alternative pathway is activated by bacterial lipopolysaccharides. Both pathways use many complement proteins and form membrane attack complexes.