8/26/13 Flashcards
How many antigen receptors must be engaged during antigen recognition?
2
What type of molecule is LFA-1 and what does it bind to on the APC?
Adhesion, ICAM-1
What type of molecule is CD28 and what does it bind to on the APC?
Signal transduction, B7-1 and B7-2 costimulatory molecules, stimulatory
What type of molecules are CTLA-1 and PD-1 and what do they bind to?
Signal transduction, B7-1 and B7-2 costimulatory molecules, inhibitory
How do adhesion molecules, such as LFA-1, change into the high-affinity state?
Chemokines of innate immune response activate them to the high affinity state
Costimulatory molecules from the APC (are/aren’t) required for T-cell activation
are
What is another co-stimulatory molecule besides B7 and what attach to and do?
CD 40, and it binds to CD40Ligand of the T-cell. It induces increased B7 expression and secretion of activating enzymes
Why do vaccines require adjuvants?
Adjuvants stimulate the production of costimulatory signals
Detail the signal transduction in a T-cell when presented an antigen by the APC
When antigen is presented, Lck of CD3 phosphorylates ITAM on zeta accessory molecule–> activates ZAP 70 on the zeta accessory molecule–> leads to 3 signaling cascades–>1. PLCgamma 1 cleaves PIP2 in IP3 and DAG–> IP3 binds to receptors on the ER and initiates release of calcium into the cytoplasm–> calcium binds to calmodulin which the complexes with calcineurin dephosphorylate NFAT–> NFAT can now move to nucleus and transactivate IL-2 and IL-2 receptor–>2. DAG activates PKC which phosphorylates IkB–>Nf-kb is released–>3. Ras and Rac initiate mitogen activated kinase cascade–> end in ERK and JNK–> ERK and JNK activate c-fos and c-jun which bind together to form transcription factor AP-1
Why are T-cells specific for the pathogen antigens more responsive to IL-2 than other T-cells in the same environment?
They express IL-2Ralpha chain
TH1 cells–> what they secrete and their actions
secrete IFN- gamma which signals macrophages to kill and signals B-cells to release complement binding and opsonizing antibodies
TH2 cells–> what they secrete and their actions
secrete IL-4,5,13–> IL-4 signals B-cells to secrete neutralizing antibodies and IgE which stimulates degranulation from Mast cells–> IL-5 stimulates Eosinophils–> IL-4,13 stimulate alternative macrophage activation (tissue repair/fibrosis)
TH17 cells–> what they secrete and their actions
secretes IL-17 which stimulates neutrophils and increased epithelial barrier protection
Cytokines/transcription factor for TH1
IFN-gamma, IL-12/ T-bet
Cytokines/transcription factor for TH2
IL-4/GATA-3
