Term
| Clonal Selection Theory: Jerne, Talmadge and MacFarlaneburnet |
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Definition
| Theory proposed to explain the specificity of the adaptive immune response |
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Term
| (CST)Lymphocytes "clones" posses...? |
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Definition
| a single type of Antigen(Ag) specific receptor |
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Term
| (CST)Antigen(Ag)binding to Antigen(Ag)-specific receptor "select" that? |
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Definition
| LYMPHOCYTES CLONE for activation, proliferation and differentiation |
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Term
| (CST)For B lymphocytes, the specificity of Antibodies(Ab) synthesized is identical to? |
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Definition
| Antigen(Ag)-receptor(surface IgM) on the surface of "selected" B lymphocyte clone |
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Term
| (CST)Immunologic tolerance(immune unresponsiveness) |
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Definition
| is explained as the DELECTION or SUPRESSION of individual Ag-specific lymphocyte clone |
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Term
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Definition
| is explained as the DIFFERENTIATION of LYMPHOCYTES CLONES INTO BOTH EFFECTOR & MEMORY B-CELL |
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Term
| (CTS)Clonal Selection is accepted by? |
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Definition
| a model for adaptive immune response explaining both B & T cell-mediated response to Antigen(Ag) |
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Term
| Kinetics of Ag-Mediated Immune Response |
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Definition
| Mature(immunocompetent) B cell circulate & populate the secondary lymphoid organ, encounter Ag & undergo clonal selection, activation, proliferation, & differentiation into plasma cells & memory B cells |
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Term
| Kinetics of Ab Response: Primary response |
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Definition
| During Lag phase, Naive B cells are activated. Increase in serum levels follows...intially IgM/later IgG. Ab produced is of relatively low affinity. Serum Ab levels peak & the ndecline relatively rapid |
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Term
| Kinetics of Ab Response: Secondary Respone |
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Definition
| During lag phase, memory B cells activated, followed by a more rapid increase in serum Ab levels. Primarily IgG but other sub isotopes may occur. Ab produced is relatively high. Serum Ab levels at much higher levels & are maintained for much longer periodsof time. |
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Term
| Cells & Functions required for Ab-Mediated Immune Response |
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Definition
| B-cells and functional BCR. Surface Ig(sIg)-(alpha/beta)+Co-receptor(CD19/21/81) |
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Term
| sIg binds specifically to? |
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Definition
| Ag free in serum, lymph or tissue fluid or presented on FDCs...activation of B cells requires the cross-linking of sIg on Bcell surface |
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Term
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Definition
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Term
| Mature naive B cells express...while memory cells will generally express...? |
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Definition
1)IgM &IgD
2)other sIg(sub)isotopes |
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Term
| _______proliferate & diiferentiate into the terminally differentiated______&_______? |
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Definition
1)Activated B cells
2) Effector cells(plasma cells)
3)Memory B cells |
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Term
| B cells also function as? |
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Definition
| Important APCs(antigen presenting cells) to Th cells(T-helper cells) |
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Term
| (Type 1) T helper(Th) cells: Experimental evidence for T cell requirement- |
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Definition
| Neonatal thymectomy studies showed that T cells are also needed for a maximal Ab-mediated response |
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Term
| Further evidence showed that...? |
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Definition
| if we destroy the mouse's lymphocytes by x-irradiation & try to reconstitute w/ B or T cells alone it is insufficient to reconstitute Ab production...ONLY WHEN B & T CELLS WERE ADDED BACK TOGETHER did it restore some Ab-production |
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Term
| T cells involved referred to as T helper cells later showed? |
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Definition
| that it exist in several subsets based on profile of cytokines produced |
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Term
| Type 2 T helper (Th2) cells: |
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Definition
| produced factors that(+) Ab response |
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Term
| Th cells required for B cells respond to? |
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Definition
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Term
| Th2 cells are mediated thru...? |
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Definition
| Both secreted soluble(helper) factors[CYTOKINES] as well as Contact-Dependent help. Important cytokines include:IL-10, IL-13, TGF-beta & others. |
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Term
| (APC): Additional studies showed that if cell suspensions containing ONLY purified T & b cells were mixed TOGETHER along with Ag relatively POOR was observed...suggest what? |
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Definition
| That additional APC was needed for efficent and maximal Ab production |
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Term
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Definition
| Correct Presentation of Ag(Ag-peptide:MHCII) ot appropriate Th cells. Also provides CO-Stimilatory for Th cell activation>B7(APC)bindng to CD28(Th cell) |
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Term
| The cell interaction w/ APC(DC,MAC,Bcells) is_____; however, B cell interaction w/ follicular dendritic cell(FDC) is______. |
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Definition
1)MHC-restricted
2)NOT MHC-restricted |
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Term
| Th cell:APC interaction + other signals generate? |
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Definition
| Th2 which secretes cytokines that (+)Ab responses |
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Term
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Definition
| For majority of proteins, the EFFECTIVE dose of any ONE Epitope is low and Insufficient, by itself, to resul in B cell ACTIVATION, PROLIFERATION & DIFFERENTIATION |
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Term
| In this case, Th cells are required to provide? |
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Definition
| Additional STIMULI to drive B cells Activation, Proliferation(clonal expansion) & Differentiaton |
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Term
| Key steps in B cell activation, proliferation, & differentiation: Step 1 |
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Definition
| Ag-BCR binding produces Signal 1 that leads to increase MHCII & B7 + CD40 on B cell |
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Term
| B cells A, P, & D: Step 2 |
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Definition
| Ag:MHCII-TCR + B7-CD28 activates Th cell |
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Term
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Definition
| Activated Th cell expresses CD40L, which binds to CD40 providing Signal 2 to B cell |
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Term
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Definition
| Activated Th cell also produces cyokines, which bind to receptors expressed on activated B cell |
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Term
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Definition
| Cytokin-Receptor binding drives & supports B cell PROLIFERATION & DIFFERENTIATION |
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Term
| Th cell-B cell conjugate formation is rquired for two reasons: |
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Definition
| Contact-Dependent and Directional Release of Cytokines |
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Term
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Definition
| Intial contact---T-B cell conjugate formation---more extensive direct cell to cell contact |
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Term
| Directional Release of Cytokines from Th cell to B cell: |
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Definition
| (+)paracrine activites of cytokine( prduce high concentration). Area of concentration directed cytokines release and ____-ligand interaction |
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Term
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Definition
| The terminally differentiated effector cell of the B cell response Actively secretes Ig of a particular isotope,which is dictated by the predominant cytokine siganal(s) present |
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Term
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Definition
| Proliferating B cells can also differentiate MEMORY B CELL tht provide a reservoir of Ag-"sensitized" cells, which allows for the GREATER& MORE RAPID Response upon SECONDARY Exposure to the SAME Ag |
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Term
| On Secondary Exposure to the same Ag: |
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Definition
| Primarily involves activation of both Memory B cells and Memory Th cells |
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Term
| T cell Independent(TI)-Ag: |
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Definition
| Certain Ag can elicit at B cell response & IgM-production independent of Th cells...T-independent(TI)- Ag |
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Term
| T-cell Independent Ag(TI-Ag) can vary greatly & include: |
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Definition
1)Polymeric molecules/structures possessing repeating epitopes
2)Microbial products possessing inherent mitigenic activity
3)Polysaccharides(NON-PROTEIN Ag) |
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Term
| In General, non-protein molecules that are NOT easily degraded w/in the body...? |
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Definition
| bind with TLRs on B cells |
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Term
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Definition
| Generate activation, proliferation & diiferentiation signals by BINDING through both BCR-Co-receptor & TLRs on B cells when at LOW doses. Many may also exhibit inherent(TLR-mediated) mitogenic activity at HIGH does |
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Term
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Definition
| Tend to be Ag possessing in effect a series of repeating epitopes...Cross linking multiple CR-CO-receptors at once on B cells surface overriding need for help |
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