Exam 16: The Immune System: Adaptive Immunity

CASE HISTORY Nathan was a ten-month-old male who had suffered much in his short life.Since birth he had experienced recurrent serious extracellular bacterial infections,all of which were resolved by antibiotic treatment.On Christmas Day,Nathan's mother discovered he had another high fever and a nonproductive cough (no mucus).He was also having trouble breathing.Fearing one more serious infection,Nathan's mother rushed him to the hospital.An X-ray showed the lung infiltrate with the appearance of ground glass.A tube was placed through Nathan's nose and into his lung,and a solution was used to wash out deep-lung contents for microscopic examination (bronchoalveolar lavage).The fluid yielded microscopic organisms.Nathan was hospitalized with pneumonia caused by Pneumocystis jirovecii,a yeastlike fungus.Although most of us have been infected with this organism,our immune systems almost always prevent disease.Finding the disease in Nathan suggested a serious immune dysfunction.An immunological workup revealed mild neutropenia (lower than normal numbers of neutrophils)but normal numbers of T and B cells,normal levels of complement,and normal complement activity.However,Nathan's blood exhibited exceptionally high levels of IgM but very low IgG and IgA levels.The physician suspected a specific defect in Nathan's T cells. Explain how a T-cell deficit could lead to this anomaly in antibody production,a task normally completed by B cells.Could this still be the source of the problem if the doctor had discovered that only IgA was high,rather than IgM?

Immunoglobulin proteins are also known as ________.

A microbe is ingested and broken into fragments by an antigen-presenting cell (APC).Which of the following would you expect to occur?

One way a pathogen may attempt to evade an immune response is by downregulating the production of Class I MHC molecules on infected cells.What type of pathogen would benefit from this adaptation and how would the pathogen benefit?

The figure shown illustrates a bacterial cell that

This figure shows the structure of an ________ antibody.

When comparing the primary and secondary immune responses,which of the following is true?

Which of the following would most directly eliminate an intracellular pathogen such as a virus?

Which of the following statements accurately describes how memory B cells become activated during the secondary immune response?

Clonal expansion of B cells occurs when a(n)

Which two antibody classes are displayed on the surface of naïve B cells?

T cells capable of killing virus-infected and cancer cells are known as ________ cells.

Rank the following macromolecules in terms of their antigenicity and explain your ranking: carbohydrates,proteins,lipids,and nucleic acids.

If you had a box of 200 beads that were different shapes and you randomly chose and linked together 3 beads,you would be performing a process analogous to the way

IgG,IgA,IgM,IgD,and IgE are all examples of

The antigen-binding site on an antibody

What is the function of an antigen-presenting cell (APC)?

The molecule indicated on this illustration of the first signal during the activation of a cytotoxic T cell (T_C)must be

Individuals with bare lymphocyte syndrome lack MHC II proteins.Which of the following could still occur in an individual lacking MHC II proteins?

Explain the role of Class II MHC in B-cell activation.