Immune System
Which of the following is correct for CD8 T cells?

CD8 T cells can kill individual virus-infected cells in a contact dependent fashion
In the thymus, CD8 T cells undergo positive selection only, whereas CD4 T cells undergo negative selection only
CD8 T cell receptor recognizes epitopes that are also commonly recognized by B cells
CD8 T cells only recognize virus-infected cells

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Immune System
Numerous antibodies can be prepared, against one antigen, each binds to unique epitopes. How is this antibody diversity generated?

By rearrangements of the DNA encoding the variable regions of the heavy and light chains
By the combination of different heavy and light chains that form the antigen binding site
Antibody proteins can physically change their shape to bind different epitopes
Both (a) and (b)

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Immune System
The role of the M cell is to

induce apoptosis in virus-infected small intestinal epithelia cells
they use their cilia to propel mucus out of the small intestine
trap virus in mucus and prevent entry
pass bacteria or virus to underlying macrophages for processing and presentation of antigen

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Immune System
Polymorphonuclear leukocytes (or PMNs)

are a type of phagocyte that can engulf and kill bacteria
can be attracted to the site of an infection following activation of complement
are derived from bone marrow stem cells
All of these

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