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Immunology Lecture 6
Adaptive Immunity
22
Immunology
Graduate
10/21/2012

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Term
Role of pathogen recognition in innate immunity
Definition
responses are based on the ability of the fixed repertoire of receptors & soluble proteins of this system to recognize the structures present in many different pathogens while not in humans
Term
Role of pathogen recognition in adaptive immunity
Definition
based on very specific, Ag-specific level of recognition of a pathogen
Term
1st Step in Dendritic cells mediating adaptive immunity
Definition
: immature iDc acquire Ags & start to differentiate into mature DC (they loose ability for phagocytosis while acquiring ability to express chemokine & other receptor & ligands enabling them to traffic to & to interact with T cells)
Term
2nd step in dendritic cells mediating adaptive immunity
Definition
mature mDc transport Ags from the center of infection to the T cells zones in the secondary lymphoid tissues
Term
3rd step in dendritic cells mediating adaptive immunity
Definition
the minute fraction of the naïve T cells, which have specificity of their Ag-recognition sites on the TCRs to the Ag delivered by Dcs, interact with these Ags in the context of their MHC Class I, or Class II molecules, thus becoming activated into effector TC, or TH cells, respectively. Via different set of cytokines DCs promote further differentiation of the TH cells into Th-1 & Th-2 subclasses (IFNgamma & TNF beta for Th-1 and IL-4, IL-5 & IL-13 for Th-2)
Term
Promote Th1 differentiation
Definition
IFN gamma & TNF beta
Term
promote Th2 differentiation
Definition
IL-4, IL-5 & IL-13
Term
Centeral tolerance
Definition
mediated via negative selection
Term
peripheral tolerance
Definition
mediated by Th1
Term
Ag recognition by T cells
Definition
antigens in the context of B cells and dendritic cells (professional antigen presenting cells) recognize epitopes
Term
Ag recognition by B cells
Definition
no help needed
Term
Allelic Exclusion
Definition
o Allelic exclusion stops the expression of RAG 1 and 2 which stops somatic recombination so that the cell if specific to one antigen
Term
2 mechanisms of diversity in variable domains of TCR and BCR
Definition
(1) Junctional Diversity (adding N and P nucleotides)
(2) Somatic recombination
Term
Positive selection for T cells
Definition
occurs in the thymus and MHC II molecules on the thymic epithelial cells select for the strongest response from the TCR. The strongest responder is moved on to a single positive cell (CD4 or CD8)
Term
Positive selection for B cells
Definition
occurs in the lymph nodes or other secondary lymphoid tissue. It involves somatic hypermutation and the strongest is picked to move on. The B cells are already antigen specific
Term
Negative selection for T cells
Definition
occurs in the thymus and the MHC class II presented by dendritic cells selects for the intermediate responder and continues onto single positive cell (CD4 or Cd8)
Term
Negative selection for B cells
Definition
occurs in the bone marrow and allows for clonal deletion of self-reactive cells
Term
Innate Immunity
Definition
Not ag sepecific
Term
Adaptive immunity
Definition
Ag specific and memory cells
Term
Co-stimulatory receptors
Definition
Co-stimulatory molecules in the T and B cells are used to produce signal 2 which causes Clonal expansion. Without co stimulatory activation, Clonal expansion will not occur
Term
Anergy
Definition
no response to antigens, occurs if there is no co-stimulatory receptors to induce signal 2
Term
• Explain the biological significance of the IL-2/IL-2R axis in the Clonal expansion of the T cells after the priming with Ag
Definition
IL-2 receptor has three chains and all three chains need to be there in order to be activated
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