Immune System
Which of the following is correct for isoantigens?

They are antigens found in some members of different species
They are antigens found in all members of a species
They are antigens found in some members of a species
They are antigens found in all members of different species

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Immune System
Polymorphonuclear leukocytes (or PMNs)

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

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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
Both (a) and (b)
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

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

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

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