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

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

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

CD8 T cells only recognize virus-infected cells
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 can kill individual virus-infected cells in a contact dependent fashion

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

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

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Immune System
Polymorphonuclear leukocytes (or PMNs)

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

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