phases of infection - lara bücher...2017/06/21 · lecture immunology summer semster 2017| lara...

Course of Infection

21.06.2017

Lara Bücher

FAKULTÄT FÜR BIOCHEMIE

Lecture Immunology Summer Semster 2017

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Course of Infection

▪ Phases of infection – overview timeline

▪ Role of innate immunity response for adaptive response

▪ Cytokines and diffrent T-cell subsets

Lecture Immunology Summer Semster 2017| Lara Bücher | 21.06.2017

Lehrstuhl für Maschinenelemente und Fördertechnik

Arbeitsgruppe Baumaschinentechnik | Professor Dr. Max Mustermann

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3Lecture Immunology Summer Semster 2017| Lara Bücher | 21.06.2017

Phases of Infectionstuhl für Maschinenelemente und Fördertechnik


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Course of a typical acute infection

▪ Pathogen replicates, level of infectious agent increases

▪ Number of pathogens exceed a certain thredhold dose of antigen

innate and nonadaptive response

▪ Immunological memory starts to be induced

▪ After 4-5 days adaptive response clears infection

▪ Dose of antigen falls below the response threshold

▪ Response stopps

▪ BUT long lasting protection through new antibodies,

residual effector cells and immological memory


Phases of Infection


Phases of Infectionhrstuhl für Maschinenelemente und Fördertechnik



Role of innate immunity response for adaptive response

▪ innate and adaptive immunity: BOTH ESSENTIAL



Innate immune reaction

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▪ Bactirial infection: inflammed tissue

▪ Activation of resident macrophages by bactirial comonents, e.g. LPS

▪ LPS acts on Toll-like receptors on the macrophages

▪ Activated macrophages secret cytokines and chemokines

especially the cytokine tumor nekrosis factor-α (TNF-α)

▪ endothelial cell activation widens blood vessels




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▪ Cytokines cause release of Weibel-Palade bodies

▪ Weibel- Palade bodies store IL-8,

von Willebrand factor (hemostasis not homeostasis), P-selectin

▪ Release of P-selectin

▪ Synthesis of E-selectin

▪ Selectins (familiy of cell adhesion molecules or CAMs):

appearance on endothilial cell surface

Binding of leukocytes leukocyte extravasation

Attraction of more and more inflammatory cells

Response is still nonspecific



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▪ Activation of potential antigen representing cells: dendritic cells

▪ Activation, e.g.:

Combination of LPS and LPB (lipopolysaccharide binding protein)

+ binding to CD14 (cell-surface receptor) and TLR-4 (Toll-like receptor)

▪ Increased synthesis of MHC class II molecules by dendritic cells

▪ Expression of co-stimulatory molecules CD80 and CD86

▪ Possible representation of antigens by CD80 and CD86

Adaptive immune reaction



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Adaptive immune reaction



▪ Carrying away antigen representing cells in lymph along with their antigen

▪ Entering secondary lymphoid tissue

▪ Attraction by chemokines ELC, MIP-ß, SLC (produceed by lymph node

stromal and high vascular endothelial cells)

▪ Eventually death of dendritic cells - but before:

▪ Activation of antigen specific naive T-lymphocytes



▪ Passing of antigen-specific naive T-lymphocytes through lymph nodes

▪ Detection of antigens represented on dendritic cells by T-lymphocytes

▪ Division and maturation into effector cells

▪ reenter the circulation

▪ High efficiency:

all naive T-cells trapped in lymph nodes

within 2 days after antigen depostion



▪ NO SENSITISATION of T-cells by infected tissue itself

▪ Activation only in peripheral lymphoid organs

by antigens brought there by dendritic cells



Cytokines and diffrent T-cell subsetsustermann

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▪ Diffrentiation of naive CD4 T-cells into 2 major classes of CD4 effector cells:

▪ During inital response to antigen in the peripheral lymphoid tissue

▪ Development of TH1 or TH2

▪ Decision between macrophage activation or antibody production




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▪ Influenced by cytokines present during T-cell activation

▪ CD4 + IL-12 + INF-γ TH1-cells

▪ CD4 + IL-4 (+IL6) TH2-cells




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▪ TH1 activation of macrophages (cell mediation)

▪ TH2 activation of B-cells (humoral response)

▪ TH1 and TH2 can regulate each other

Outlook:

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Thanks!

References: Janeway, Immunobiology, 8th, p. 454-470

phases of infection - lara bücher...2017/06/21 · lecture immunology summer semster 2017| lara...

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