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ADAPTIVE IMMUNITY.
T CELLS
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Adaptive immunity
IMMUNOLOGY
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Classification of lymphocytes
IMMUNOLOGY
T lymphocytesB lymphocytesNK cellsNKT cellsImmatureMatureResting (nave)ActivatedEffectorMemory cellsRegulatory
Antigen receptors
Competence
Function
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Cell count 20-40% of WBC 1000-4800 Ly/uL
IMMUNOLOGY
CD4% = 32.14 - 59.30%
CD8% = 15.05 - 36.11%
CD4 Abs# = 522-1594/uLCD 8 Abs# = 135 1047/uLCD4/CD8 Ratio = 0.67 - 3.11
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Immunophenotyping
IMMUNOLOGY
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T and B cells
IMMUNOLOGY
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T lymphocytes Effectors of cell mediated immunity Functions:
Activate phagocytes (Th1)Kill infected cells (CTLs)
Stimulate production of antibodies (Th2)
T cell receptor recognition (TCR) MHC-restricted
IMMUNOLOGY
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Lymphocyte development Developmentand maturation
occurs in the central lymphoid
organs Commitmentof progenitor cells to
the T or B lineage Proliferationof progenitor cells
driven by IL-7 Rearrangementof antigen receptor
genes Selectionof lymphocytes with the
correct immune repertoire Differentiationof B and T cell
subpopulations
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Transcriptional regulation T-cells: Notch-1, GATA-3 B-cells: EBF, E2A, Pax-5
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T-cell development Cell-surface markersAg receptor - TCR Thymus= major site of maturation. Thymocytes..
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T cell maturation Sub-capsular sinus cortex medulla
Interaction with thethymic environment
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Selection checkpoints
Pre-antigen receptorFunctional antigen receptorPositive selectionNegative selection
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Positive/Negative selection in the
thymus
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T cell markers
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T cell subsets Tc (cytotoxic) - CD8+ Th (helper) - CD4+ NKT cells (CD1d restricted)
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T helper subpopulations
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TCR TCR recognizes peptide bound to a MHC
molecule expressed on the cell surface
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TCR types Heterodimer, 2 polypeptide chains
!"T cells (95 % peripheral T cells)#$T cells (epithelia)
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TCR complex
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TCR complex CD3 protein (#, $, %) &chain CD4 and CD8 coreceptorsAccessory molecules:
CD2, LFA-1, CD28, CD45R
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Antigen receptor gene rearrangement Functional Ag receptor genes
in immature B and T cells V(D)J recombination Germline organization - all cell
types
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T cell activation
IMUNOLOGIE
Signal 1:Interaction betweenTCRand MHC/antigen complex
Signal 2:Co-stimulatory interactionsbetween CD28molecules on
the T cell and B7molecules
on the APC
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Tc response
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Th regulation
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SummaryWhat happens during the adaptive immune response Classification of lymphocytes T cell development T cell markers T cell subsets TCR T cell functions T cell activation