Exam 2- Adaptive Immunity Part 3-Activation Flashcards
Activation of T cells requires
- TCR complex-coreceptor (CD4 or CD8) and cognate protein presented in MHC II or MHCI on APCs
- Costim of B7 on APC to CD28 on T cell
- IL-2 for expansion
TCR complex coreceptors
CD4 or CD8
Costim signal from APC to activate T cell
B7-which will bind Cd28 on Naive T; stabalized by glycoprotien cells
Required for T cell exapansion and differentiation
IL-2- a type of cytokine
Needed for T cell to synthesize and secrete IL-2 (type of cytokine)
Co-stim: which is B7 transmembrane protein that binds Cd28 on Naive T cell
Clonal Selection
Selection of T cell based on exact epitope
TCR contacts (epitope or MHC II)?
Epitope-while the MHC II binds CD4+
T cell gets IL2 from
itself, autocrine in case of exogenous
Clonal expansion
Cell rapidly doubles when IL-2 is present
___ cells activate macrophages –> ROS via ____
TH1 cells; via IFN gamma (post MHCII binding)
Activated macrophage
ROS- Oxygen radicals, nitric oxide and proteases which is an important defense against intracellular bacteria
ROS activated macrophages are important in defense against
Intracellular bacteria
signal 1 of Cytotoxic T cell activation
recognize processed engogenous antigen on MHC1 with APC
Signal 2 of CTL activation
Co-stim from APC (i.e. B7)-T cell undergoes clonal selection in secondary lymph tissue
CTL cells signal 3
Need an additional signal; from TH1 cells which is IL2-b/c these things kill!
CTL cells need what extra component
IL-2 from TH1-since only want CTL if need them
TH1 –> IL2 –> CD8+ cells effect
upregulate IL2 and receptors, can now make own IL2 and expand
____ cells recognize antigen directly via their ___ receptors
B cells-IgG receptors
____ cells make and secrete antibodies (secreted Ig)
Plasma cells/B cells
T independent Antigens
Rare, highly repetitive antigens (polysaccharides with repetitive subunits)
Weak stimulation to make IgM antibodies
No memory cells
No class switching
Rare, highly repetitive antigens (polysaccharides with repetitive subunits)
T independent antigens
No memory cells
T independent
No class switching
T ind
T-Dependent Antigens
Common, majority
Antigen presented with MHCII to TH2 cell (need contact and costim)
TH2 produces cytokines –> activate B cell
Strong memory
Class switching (make antibodies other than IgM)
Develop strong memory
T Dependent Antigens
Class Switching
T Dependent Antigens
