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Tcell receptor
has variable and constant regions, alpha and beta chains, undergoes somatic recombination, only has ONE antigen binding site
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Helper T cel
have CD4 receptors, bind to MHC II receptors, secrete cytokines (mainly interluekins)
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CD4
Receptor that helps Tcell receptor bind
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Autostimulation Cytokines
secreted by Th Cells to cause Th cell proliferation; they then differentiate into memory T cells supressor T cells
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Cytotoxic T cell
have CD8 receptor, bind to MHC I, secrete perforin for apoptosis
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CD8
helps T cell receptor bind to MHC I
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Perforin
secreted by Tc to kill infected cell by apoptosis
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Granzymes
released by activated Tc cell to induce apoptosis
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First Signal
Binding of TCR to MHC and antigen; binding of CD 4 or 8 to MHC
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Second Signal
binding of CD 28 to B7
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Co-Stimulatory peptide B7
produced once the phagocyte has bound a PaMP; ensures dendritic cells have seen a pathogen
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CD28
receptor on Tcell which binds B7
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Interlukin-2
stimulates the Tc cell as a second signal to activate a Tc cell
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Naive T cell
T cell that hasn't seen a pathogen
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Effector T cell
T cell that has bound to pathogen on MHC and CD28
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T dependent Antigen
must be stimulated by T cell to make antibodies
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T independent Antigen
B cells that can proliferate without a Th cel by binding an antigen to many receptors n the B cell at once
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Protein Conjugate vaccine
T independent antigen is attached to a proein; b cell has typical response and makes antibodies and memory B cells
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T regulatory cells
shut off immune response once the antigen is gone
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T memory cells
reactivated just by binding the antigen; do not need to bind CD28/B7; last 5-10 years
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Clonal deletion
occurs in thymus during T cell development to delete T cells that recognize self antigens
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Positive selection
T cells must bind to MHC I in thymus to get nutrients to develop; if they don't they die
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Negative Selection
If binding to a self antigen in thymus occurs they die
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Natural Killer Cells
Binds to the Fc part of an antibody bound to a pathogen; releases perforins to cause apoptosis
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Cancel Kill Signal
If a MHC I receptor is present on a cell, it isn't killed by NK cells
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