Immuno Six: B Cells And T Cell Ontogeny

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adhesive molecules

Back 1

surface molecules that bind counter molecules on other cells causing close contact between the cells

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afferent lymphatics

Back 2

lymphatic vessels that enter the lymph nodes

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alpha-beta TCR

Back 3

refers to the T cell antigen heterodimeric receptor on more than 90% of T cells

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alternative splicing

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the process by which mRNA is spliced to create either a mu or a delta heavy chain constant region

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anergy

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the process by which a stimulus causes cells to become non responsive

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apoptosis

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the process by which cells under go self-induced suicide

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autoreactive

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refers to immunological responses against self antigens

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BCR

Back 8

the B cell receptor - refers to the antigen specific receptor on B cells

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CD19

Back 9

a molecule that is present on all B cells - therefore a panmarker

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CD3

Back 10

a molecule that is present on all T cells - therefore a panmarker

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CD79a

Back 11

expressed in association with CD79b - the complex is expressed on the cell surface with BCR

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CD79b

Back 12

expressed in association with CD79a - the complex is expressed on the cell surface with BCR

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combinatorial diversity

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a term that refers to the multitude of gene segments that comprise variable regions of BCR and TCR

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death by neglect

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refers to the phenomenon by which developing thymocytes die because they do no receive appropriate signals

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diversity (D)

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a gene segment that encodes a segment of the heavy chain Ig or the beta chain of the TCR but not light chain or TCR-alpha

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down regulation

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the process by which expression of cell surface molecules is decreased

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efferent lymphatics

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lymphatic vesels that leave tissues

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gamma-delta TCR

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refers to the T cell antigen heterodimeric receptor on about 10% of the T cells

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germline DNA

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refers to genomic DNA, DNA that has not been altered by recombinatorial events

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glycocalyx

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a prominent filamentous layer on the surface of specialized endothelial cells

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high endothelial venules

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special post-capillary venules that serve as sites for lymphocytes to exit blood and enter lymph node parenchyma

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integrin

Back 22

adhesion molecules that induce firm contact between cells that have appropriate counter molecules

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joining (J)

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segment of DNA that encodes for a segment of the light and heavy chain variable regions (as well as TCR alpha-beta)

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junctional diversity

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the heterogeneity that results from either the removal or addition of bases at the junction of DNA segments V, D, J

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kappa

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one of the two light chain constant regions - the other is lambda

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L selectin

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a molecule whose interaction with counter molecules causes lymphocytes to roll on the endothelium

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lambda

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one of the two light chain constant regions - the other is kappa

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lineage commitment

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the process during T cell development in which CD8+, CD4+ thymocytes become CD8+ or CD4+ only

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matrix metalloproteinases

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enzymes that cause the degradation of endothelial cell wall to allow cells to pass from the blood vessels to tissues

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mIg

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membrane immunoglobulin, same as BCR

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negative selection

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destruction of developing thymocytes as a result of strong signals when thymocytes interact with thymic epithelium

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panmarker

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refers to a cell suface molecule present on a particular cell type and not usually present on other cells

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positive selection

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the proliferation of developing thymocytes when they receive the appropriate signals

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pre-BCR

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the precursor complex expresed on developing B cells prior to the expresion of the BCR complex

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pre-Tα

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the chain that associates with the beta chain TCR to form a precursor complex on the developing T cells in the thymus

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pseudo light chain

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the chain that is associated with the heavy chain to form a precursor complex on developing B cells

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recombination activating genes (RAG-1 and RAG-2)

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genes that encode proteins required for somatic recombination of variable region of B cell or T cell angigen receptors

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somatic recombination

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the process by which DNA segments are rearranged to form a variable region for either the B cell or T cell receptor

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TCR

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the T cel receptor on the majority of T cells - it recognizes antigen-MHC complexes

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TCRα

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the alpha chain of the T cell receptor

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TCRβ

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the beta chain of the T cell receptor

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terminal deoxynucleotidyl transferase

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an enzyme capable of catalyzing the template independent insertion of nucleotides between variable region segments

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tolerance induction

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the process by which the immune system remains non responsive to self antigen

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transcription

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the process by which DNA is converted to mRNA

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translation

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the process by which mRNA is converted to protein

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triggering threshold

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the level of signal intensity beyond which cells are destroyed

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variable (V)

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the region present in each chain of the B cell and T cell antigen recognizing receptors