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
recognize peptides associated with MHC class II molecules
are secreted out into the environment to bind antigens

ANSWER DOWNLOAD EXAMIANS APP

Immune System
Polymorphonuclear leukocytes (or PMNs)

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

ANSWER DOWNLOAD EXAMIANS APP