1 / 20

Topics

Topics. Immune regulation  T cells Fc receptor binding in B cells Early response mechanisms Antigen concentration Immunological memory. Immune regulation. Idiotypic network.

edeline
Download Presentation

Topics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Topics • Immune regulation •  T cells • Fc receptor binding in B cells • Early response mechanisms • Antigen concentration • Immunological memory MICR 415 / 515 / 682

  2. Immune regulation MICR 415 / 515 / 682

  3. Idiotypic network Variable regions of Ab are able to serve as antigens that elicit the production of anti-idiotipic Ab by the same individual i. e. Modulation of the immune response in Schistosomiasis MICR 415 / 515 / 682

  4. Regulatory T cells • The immune system has to: • Protect the host from pathogens • Distinguish between self and non-self structures • Distinguish harmful from innocuous Ag to prevent non-essential responses • Induction of Ag-specific self tolerance MICR 415 / 515 / 682

  5. Tregs = CD4+ regulatory T cells • CD4+ CD25+ (IL-2 R  chain) • Naturally occurring • Cell-cell contact (molecules not yet defined) • Depletion leads to autoimmune diseases • 5 – 10 % of all peripheral CD4+ T cells • Anergic (hyporesponsive) • Suppress activation of CD25- T cells • Inhibit IL-2 transcription • Th3 and Type 1 T regulatory (Tr1) • Contact independent • IL-10, TGF-β • Altered state of development (not an independent cell lineage) MICR 415 / 515 / 682

  6.  T cells • TCR composed of   chains • 2 sets • Found in lymphoid tissues of all vertebrates • Display some diversity of TCR • Intra-epithelial in some vertebrates • Limited diversity of TCR • Limited recirculation • Recognize ligands expressed by infected cells • Heat shock proteins, MHC IB molecules • Direct and rapid response to the precence of infected cells MICR 415 / 515 / 682

  7.  T cell as regulators of IR • Mice deficient on  T cells mount exaggerated responses to foreign and to self Ag. MICR 415 / 515 / 682

  8. Fc receptor binding in B cells • Engagement of Fc receptors in B cells reduces the B activation and reduces production of antibodies MICR 415 / 515 / 682

  9. Early response mechanisms • Th0 differentiate into Th1 and Th2 and determines if the response is cellular or humoral • Cytokines present at the site of proliferation MICR 415 / 515 / 682

  10. Th1 induction • IL-12, IFN- • Produced by dendritic cells, macrophages, NK cells in response to viral infection and invasion by some intracellular bacteria MICR 415 / 515 / 682

  11. Th2 induction • IL-4 and IL-6 • Produced by NK1.1 CD4 T cell • Invariant TCR • Do not require TCR:MHC interaction of recognition • Recognize some MHC IB molecules MICR 415 / 515 / 682

  12. MICR 415 / 515 / 682

  13. + - + - Th 2 Th 1 • IL-4 • IL-5 • IL-10 • IL-2 • IFN- Immunoregulation Th0 MICR 415 / 515 / 682

  14. Antigen concentration • High amounts of Ag -> Th1 • Low amounts of antigen -> Th2 • Strong MHC-peptide to TCR interaction ->Th1 • Weak MHC-Peptide to TCR interaction -> Th2 • High affinity of peptide to MHC ->Th1 • Low affinity of peptide to MHC ->Th2 MICR 415 / 515 / 682

  15. Antigen concentration MICR 415 / 515 / 682

  16. Immunological memory • Effective responses eliminate pathogen or Ag from the system • Removal of most effector cells as part of the restoration of tissue integrity • Cells die via apoptosis and are cleared by macrophages • Cells that survive become memory cells. • T cells survive almost indefinitely. MICR 415 / 515 / 682

  17. MICR 415 / 515 / 682

  18. Immunological memory • B cells develop primary focy of proliferation 5 days after inoculation of Ag • Initial Ab production Early response Trapping of Ag FDC presentation (iccosomes) MICR 415 / 515 / 682

  19. Differentiation, germinal center formation • Somatic hypermutation, selection • Exponential proliferation for 2 or 3 days (6 or 7 cell division cycles) • 90% Differentiation into plasma cells (2 – 3 day life span, then apoptosis) • 10% life longer, fate is unknown MICR 415 / 515 / 682

  20. Germinal centers last for 3 – 4 weeks • Some B cells continue to proliferate for months • Migrate to the mucosas • Differentiate into plasma cells • Last for years MICR 415 / 515 / 682

More Related