recap

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41.6 recap

Failures of the immune system include allergic reactions (caused by hypersensitivity to antigens), autoimmune diseases (caused by reactions against self antigens), and immune deficiency disorders.

learning outcomes

You should be able to:

  • Summarize the responses made during immediate hypersensitivity.

  • Describe how desensitization can be used to minimize allergic reactions.

  • Summarize the hypotheses that explain how autoimmunity can occur.

  • Outline experiments to test the effectiveness of an HIV vaccine.

Question 1

Some people are allergic to peanuts. Outline the events that characterize the immune reactions involved.

An antigen in peanuts binds to a B cell displaying an anti-peanut protein antibody. This causes production of a clone of plasma cells that initially make IgG and then switch to IgE. The IgE binds to mast cells, which release histamine, causing symptoms of distress.

Question 2

There has been recent progress in treating peanut allergy by desensitization. How does this work?

Desensitization involves giving the person a small amount of peanut protein that provokes IgG synthesis but not IgE, so mast cells are not stimulated.

Question 3

A new cancer treatment involves promoting autoimmunity by designing a drug to inhibit CTLA4, a protein on T cells that normally blocks them from mounting an autoimmune response. How does this treatment work? What might be its side effects?

The anti-CTLA4 treatment for cancer removes inhibition of the T cell cytotoxic response to self antigens. This causes T cells to bind to and kill cancer cells. A side effect might be generalized autoimmunity.

Question 4

Development of an effective HIV vaccine requires that a person being vaccinated develop both cellular and humoral immunity against HIV. What experiments would you perform to test whether both types of immunity developed in people given a potential new vaccine?

Experiments might involve testing vaccinated people for neutralizing antibodies against HIV (humoral immunity) and looking for T cell activity against HIV-infected cells (cellular immunity).