Exam 2: Cellular Immune Response Flashcards
Cellular immune response is provided by which cells
T cells
What does the cellular immune response provide immunity to:
intracellular bacteria and viruses, fungi, protozoa, tumors
T cells can recognize antigen only when it is presented by which cells?
APC, by self MHC molecules
T Cells mediate the process of
activating infected cells and destroying the intracellular organism
Endogenous antigen is presented on which MHC molecule?
MHC type 1
T Cell cytotoxicity is characterized by:
membrane blebbing, nuclear fragmentation and phagocytosis of the dieing cell
initiator caspaces
2, 8, 9, 10, 14
Initiator caspaces are activated by
multimoleculular death complexes
Effector caspaces
3, 6, 7
Effector caspaces function to
break down cellular structures
Inflammatory caspaces
1, 4, 5, 11
Inflammatory caspaces are activated by
multimolecular inflammasomes
Intrinsic pathway of T Cell cytotoxicity (mitochondrial pathway)
- Damaged mitochondria trigger pathway
- Cytochrome C triggers formation of apoptosome
- Initiator caspace 9 is activated
- Triggers cascade of Effector Caspaces
- Apoptosis
Extrinsic pathway of T cell cytotoxicity (death receptor pathway)
- TFN-alpha binding Fas triggers pathway
- Stimulates initiator caspace-8 and 10
- Triggers cascade of Effector Caspaces
- Apoptosis
What are the major morphological features of cell death by apoptosis?
Normal cell– Clumping of chromatin, blebbing and loss of organelles – Nuclear fragmentation, Apoptotic bodies – Apoptotic bodies
T Cell activation requires
- IL12 from activated DC cell
- Antigen- MHC complex on abnormal cell
- IL-2 and IFN-gamma secreted by TH1
Perforins function to
create channels in cell membrane
Granzymes function to
destroy shit in the cell and activate caspace-3
What are the steps in the Perforin Pathway (intrinsic pathway)?
- Adhesion phase
- Lethal Hit
- Cell death
What occurs during the adhesion phase of the perforin pathway?
CD8 bind MHC 1, costimulation of T cells and adhesion molecules
What occurs during the lethal hit phase of the perforin pathway?
T cell sends granules containing perforins, granzymes
and granulysin; triggering caspace 3, then dna fragmentation
What are the steps in the CD95L Extrinsic Pathway?
- Binding of TCR to MHC 1
- CD95 L binds CD 95 Fas
- Formation of DISC-death inducing signaling complex
- Activates initiator caspace-8 and 10
- Initates caspace 3
- Apoptosis
What cytokines are secreted by Th1 cells to stimulate antigen presenting cells to kill intracellular bacteria?
IFN- gamma and IL-2
Macrophages and DCs phagocytosis and secrete what cytokine to activate NK cells?
IL-12 and TNF alpha
Nk cells secrete what cytokine to activate macrophages?
IFN-gamma
Full activation of marcophages requires?
Th1 response to IL12 and TNF alpha, to secrete IFN-gamma and IL2 to activate the macrophage
Classical activation of macrophages is facilitated by?
TH1 secreting IFN-gamma and TNF alpha, activation M1 macropages
M1 macrophages are considered
proinflammatory cells, secreting Il-1, -6, -12, -23, No and iNOS
Alternative activation of macrophages is facilitated by?
Th 2 cells and Treg cells secreting IL-4, 10 and 13 to activate M2 macrophages
M2 macrophages are considered
antiinflammatory cells, secreting IL-1RA, IL-10 argnizase and TGF beta
activated macrophages function to
resolve inflammation, wound repair, extracellular matrix production, cell proliferaiton, angiogenesis
What is an effector T cell?
Memory T cells that reside in inflamed tissue and immediately attack invaders
Effector Memory T Cell Function
Increase Il-2 receptor, adhesion molecules, IL-4 and IFN-gamma and TCR stimulation
**IL15 survival of Tc memory cell
T Cell cytotoxicity induces apoptosis on the target cell by the activation of caspace cascade (Extrinsic and intrinsic pathways). T/F
True
The extrinsic and intrinsic pathways triggers a cascade of enzymes activation to induce apoptosis on the target cell. These pathways are activated by the interaction of the T cll receptor and the MHC type 1 and antigen. T/F
True
Superantigens
- not MHC restricted -Bind T and APC together
* some stimulate a LG. amount of cytokines that trigger toxic shock syndrome
