Cells of the immune system

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• Cells of the immune system

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Cells and Tissues of the immune system

• The cells of the adaptive immune system are
  normally present
• a)Circulating cells in the blood and lymph
• b)Anatomically defined collection in lymphoid
  organs
• c)Scattered cells in all tissues

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• Lymphocytes
• Antigen presenting cells(APC)
• Effector cells

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Cells of the immune system (lymphocytes)

• Lymphocytes are the only specific cells and are
  responsible for specificity and memory
• They are 3 subsets ,different in functions and
  protein products but not in morphology
• 1-B cells
• 2- T cells(helper and cytotoxic)
• 3- Natural killer (NK) cells

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Overview of lymphocyte development

• Commitment
• Proliferation(IL-7)
• Rearrangement
• proliferation
• Selection

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B lymphocyte development

• stem cell
• Pro B cells
• CD19,CD10, µ heavy chain rearrangement
• Pre B cells
• Pre antigen receptor expression
• immature B cells
• IgM BCR expression,independent of antigen and
  their encounter with it ,receptor editing,cell
  death,functional unresponsiveness
• Mature B cells

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• Rearrangement of Ag receptor genes is the key
  event in lymphocyte development.
• There are two checkpoint steps
• One of them,successful production of one of the
  polypeptide chains of two
• The assembly of a complete receptor

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• Pre-Ag and Ag-receptors deliver signals to
  developing lymphocytes that are required for the
  survival of them
• Positive selection and Negative selection
• Clonal deletion
• Receptor editing

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Mature B cells

• Fetal liver stem cells .B-1 B cell
• Bone marrow stem cells..B-2 B cells.marginal
  zone B cells and follicular B cells with Both IgM
  IgD
• B-1 B cells (CD5)
• found in peritoneum and mucosal sites
• Limited diversity
• Secrete IgM
• Marginal zone B cells
• Located in the spleen
• Express IgM and CD21
• Respond to blood-borne microbes

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B cell surface markers

• B cell receptor(Ag recognition)
• CD19 (B cell activation)
• CD21or CR2 (B cell activation and EBV receptor)
• CD25 (binds IL- 2)
• CD27 (memory B cells )
• CD40 (B cell activation)
• CD80 or B7(costimulator for T cell activation)
• CD81 (B cell activation)

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T cell subpopulations

• T lymphocytes mature in the thymus
• Mature T cells Th and Tc,TR
• T cells have CD4, CD8,TCR(aß ??)
  ,CD28,CD40L,CD2,CTLA-4(memory T cells have IL-7
  R)
• T helper cells have 2 subsets Th1 and Th2 are
  differentiate by cytokine pattern that they
  produce.
• Th1IFN-?
• Th2 IL-4 , IL-5,IL-10, IL-13

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• Two types of molecules produced by nonlymphoid
  thymic cells important for T cell maturation
• Class-I and II MHC
• Cytokines and chemokines
• CCR9-----CCL25
• CCR7------CCL19,21

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???? Th1

• ????? ??? ??? ???? ?? ???? ??? T ????? ????
  ???????? ??? IL-12 ? IFN- ?
• ?? ???? ?? ?????? ???? ???? ?? ???? ?? ???? ???
  ???????? ? ?????????? ? ???? ??? NK ?? ???? ??
  ????
• ??? ????? ??? ??? ????? ?? ????? ????? ???
  ????? ???? ??? ?? ???? ?? ????? ???? ???????? ??
  ??? IL-12,IL-18 ? ????????? ??? ??? ?? ?? ???.
• IL-12 ??? ???? ???? ????? ???? ?? ? Th1 ????? ??
  ???. ?? ??? ????? IL-18 ??? ?????????? ????? ??
  IL-12 ?????????? ?? ?? ????? ?? ????? ??? ??????
  ??? ?????? ???? ???? ??? Th1 ???? ?? ????.
  ?????? ?? ??? ?? IL-12 ? ?? IL-12R ? ???? ??
  ????? ??? ???? ????? ??????.

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???? Th2

• ????? ??? ??????? ?? ???? ??? T ?????? IL-4
• ?? ???? ?? ??? ?? ? ????? ?? ????? ?? ????.
• ??? ???? ?? ???? ?? ???? ????? ???? ? ????????
  ???T ?? ????
• ????? ??? IL-4 ??? ???? ?? ????? ???? ??? T CD4
  ?? ???? ??? Th2 ????
• ???? ????? IL-4 ????? ??? ?? ????? ???? ??? Th-2
  ?? ???? ?? ?? ? ??????? ?? ? ?????????? ?? ??
  ????? ?? ???? ??? ????? ? ??? ?? ?? ???? ?? ????.

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???? Th17

• ???????? ???? ?? ????? ???????? ??? ?????? ????
  ??? ?? ?? ???? ?? ????? ??? ????????? ? ?????
  ????? ?? ????.
• ?? ???? ??? ????? ????? ?? ???? ?????? ???
  ?????? ???? Dectin-1 ? ???? ??? ???????? ??
  ????? ? ???? ?? ????? ?? ????? ???????? ???? ???
  IL-1 , IL-6 ? IL-23 ?? ????.
• IL-23 ??? ?? ????? ? ?? ????? ?? ????? ??????
  ???? ??? Th-17 ????? ????.
• ????? ???? ??? TH-17 ???? IL-4 ? IFN-? ????
  ?? ??? ????? ??? ???? ??? ??? Th1 ? Th2 ???? ??
  ????? ???? ??? Th17 ?? ???.
• ???? ????? TGF ß ?? ??? ?? ???????? ??
  ??????? ??? ?? ???? IL-1 ? IL-6 ???? ????? ?????
  ???? ??? Th-17 ?? ????. ???? TGF ß ???????
  ?????? ?? ????? ???? ?????? ???? ??? Th17 ???.

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• ??? ???? ?? IL-21 ????? ?? ???? ?? ??? ?? ?????
  ?? ?? ??????? ????? ????? ????? ???? ??? Th17 ??
  ?????? ????.
• ?????? ?? ????? ????? ???? ??? Th17 ??? ??????
  ??? ????? ?????? ???? ??? ????? ?? ??? ?????
  ???????? ??? ?????? .
• ???????? ?? ??? ?? ??? ?????? ??? ????? ??????
  ???? ?? ??? ????? ?????? ???? Jobs syndrome ??
  ???.
• ?? ??? ??????? ???? ??? ????? ????????? ? ?????
  ????? ?? ??? ?? ???? ????? ??? ?? ???? ???? ???
  Th17 ?? ????.
• ??? ???? ?? ?? ???? ??? ????? ????? ?? ??????
  ????? ???????? ???? ?? ???? ???? ????? ????
  ?????? TGF-ß ? ???? ????????? ?? ?? ??? ???? ????
• ??? ??????? ???? ?????? ?????? ??? ?????? ????
  ?? ??????? Th17 ??? ???? ?? ???? ???? ????? ?? ?
  ???????? ???? ?? ????? ????.

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????Follicular Th(T FH)

• ??? ???? ??????????? ??? ???????? ???? ???? ???
  B ???? ??? ????? ?? ????? .????? ????? ?????? ???
  ??? ????? CXCR5 ?? ??? ???? ???? ??? ?? ????
  ?????? ???? ??? ????? ??????? ??? ???????? ?????
  ?? ???.
• ??? ???? ?? ??? ???? ?? ????? ??? ????? ????
  ????????? ?? ???? ?? ????.
• ?? ????? ??? ??? ???? ?? ????? ???????? ???
  ??????? ? ???? IL-21 ? ???? ????? ?????? ??????
  Bcl6 ?? ????.

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???? Regulatory T

• ??? ????? ?? ???? ??? T CD4 ????? ?? ???? ???
  ????? ?? ???? ????? ? ???? ????? ??????? ?????
  ???? ?? ??? ?? ????..?? ????? ??? ??? ???? ??
  ????? ?????? ????? ?????? ?????????? 2 (IL_2R?
  chain) ?? CD25 ? ?????? ????? ?????? FoxP3 ?
  ????? ????? CTLA-4 ??????. ??? ?? ??? ???? ?? ??
  ????? ???? ?? ???? ????????? ??? ???? ????.

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NK T cells

• IL-4,IFN-?
• 5-15
• Help marginal B cells for Ab production against
  lipid antigens
• Not MHC restriction
• ??TCR
• CD56

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• MHC-I MHC-II
• Cytokines(IL-7)
• chemokinesCCL21,CCL19(CCR7)

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T cell receptor
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T cell trceptor
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Clonal selection
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Effector cells

• Activated Th cells
• Cytolytic T cells
• Plasma cells
• Mononuclear phagocytes
• Nk cells

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Phagocytosis
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NK cell activity
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Dendritic cells

• Coventional Dc
• Plasmacytoid Dc