Immunology Flashcards
What is required for the activation of naive CD4 and CD8 T cells?
APC’s to present antigen with MHC, recognized by TCR and co-stimulatory signal by B7 that is recognized by CD28 on T cell
Which APC is the only one that can activate naive T cells?
Dendritic cells
What are the two lineages of T cells?
alpha-beta
gamma-delta
How do alpha-beta T cells differ from gamma-delta T cells?
Alpha-beta T cells differentiate into CD4 and CD8 T cells and require MHC recognition
Gamma-delta T cells do NOT require specialized recognition (instead they recognize lipids and are not as specific)
Where does T cell development occur in the body?
Thymus
Which cell in the thymus is responsible for T cell positive selection?
Cortical Epithelial Cells
What is T cell positive selection?
T cells that bind with moderate affinity to the self-cortical epithelial cell MHC molecules receive signals that allow them to survive
What is T cell negative selection?
Double positive thrombocytes (immature T cells) that bind too tightly to self-MHC molecules are signaled to undergo apoptosis
Which cells in the thymus are responsible for T cell negative selection?
Dendritic cells and macrophages
What marker do NK cells express?
CD56 (sometimes CD16)
Where do NK cells develop?
Bone marrow
What is the mechanism by which NK cells respond to early viral infections and induce apoptosis in virally infected cells?
Cytotoxic perforin and granzymes (same effector mechanism as CD8 T cells)
Which cytokines do NK cells secrete and what do they do?
IFN-gamma which activate macrophages
What do NK cells recognize on the surface of potential target cells and what are their receptors called?
Recognize MHC (HLA) molecules on potential target cells. NK cells have inhibitory receptors that recognize them.
What are small lymphocytes?
Inactive B cells and T cells
