Immune System
Polymorphonuclear leukocytes (or PMNs)

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

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

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

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Immune System
The role of the M cell is to

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

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

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

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