Immune System
The role of the M cell is to

pass bacteria or virus to underlying macrophages for processing and presentation of antigen
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

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

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

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Immune System
T cell receptors (or TCR) on CD4+ T cells

recognize peptides associated with MHC class I molecules
are secreted out into the environment to bind antigens
recognize peptides associated with MHC class II molecules
recognize peptides not associated with MHC molecules

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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?

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

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Immune System
Which of the following statements is false regarding B cells?

B cells can undergo class switching and produce a different antibody type
B one marrow stem cells migrate to the thymus and develop into B cells
B cells synthesize antibodies and put them on their cell surface
B cells that recognize high concentrations of antigens (self) in the absence of other signals undergo apoptosis in the bone marrow

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