1 / 15

Do all immune complexes lead to tissue injury? - Large complexes are removes by phagocytes

Do all immune complexes lead to tissue injury? - Large complexes are removes by phagocytes - Medium and small complexes are pathogenic. Type IV Hypersensitivity (Cell mediated) Participants: - Antigen presenting cells (macrophages) - T lymphocytes - Cytokines. Two types:

doyle
Download Presentation

Do all immune complexes lead to tissue injury? - Large complexes are removes by phagocytes

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. Do all immune complexes lead to tissue injury? - Large complexes are removes by phagocytes - Medium and small complexes are pathogenic

  2. Type IV Hypersensitivity (Cell mediated) • Participants: • - Antigen presenting cells (macrophages) • - T lymphocytes • - Cytokines

  3. Two types: • 1) Delayed type Hypersensitivity: • Mediated by CD4+ T cells (helper) • 2) Direct T cell cytotoxicity: • Mediated by CD8+ T cells (cytotoxic)

  4. 1) Delayed type Hypersensitivity (DTH): • Tuberculin test is the prototype 24-72 hrs 24 - 72 hrs - Mononuclear cells around blood vessels - Increased vascular permeability - Escape of plasma proteins & fibrin - Endothelial swelling and hypertrophy

  5. 1) Delayed type Hypersensitivity (DTH): • - Exposure to TB protein • - Differentiation of CD4+ T cells to sensitized TH1 cells • - Injection of PPD into skin (re-exposure to antigen) • - Recruitment of sensitized TH1 cells, secretion of cytokines

  6. Cytokines involved in DTH: • - IL-12: • Produced by macrophages and dendritic cells • Responsible for induction of TH1 response • - IFN-ϒ: • Key mediator for macrophage activation • Responsible for formation of granuloma • - IL-2: • Causes proliferation of T cells at site of DTH • - TNF and lymphotoxin: • Through prostacyclin increase blood flow • Through P-E selectins promote margination and diapedesis • Induces other chemotactic factors

  7. Persistent / non-degradable antigens (eg. TB bacilli in lungs / tissues) - Accumulation of macrophages over 2-3 weeks - Macrophages transform to “epithelioid cells” - Granuloma formation occurs

  8. Clinical situations (DTH): - Intracellular pathogens (TB, leprosy, fungi, parasites) - Transplant rejection - Tumor immunity - Contact dermatitis - Autoimmune diseases like Type I diabetes and Multiple sclerosis

  9. T Cell-Mediated Cytotoxicity: - Role of CD8+ T cells (cytotoxic T Lymphocytes), Class I MHC

  10. Clinical situations (CTL): - Transplant rejection - Resistance to viral infections - Tumor immunity

More Related