Cytokines and CD4 T cell effector functions • Activated T cells change their migration patterns • Activated CD4 T cells can make different types of cytokines • There are many cytokines involved in immune reactions • Some are made by APCs, others by T cells • Cytokines can work together or in opposition • CD4 Th1 responses are dominated by IFN-production and a phagocytic cell response. • CD4 Th2 responses are dominated by IL-4 production and the stimulation of an "allergic" type response. • The class of the response may be important Chapter 6
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Cytokines and CD4 T cell effector functions Activated T cells change their migration patterns Activated CD4 T cells can make different types of cytokines.
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Cytokines and CD4 T cell effector functions
• Activated T cells change their migration patterns• Activated CD4 T cells can make different types of
cytokines• There are many cytokines involved in immune reactions• Some are made by APCs, others by T cells• Cytokines can work together or in opposition• CD4 Th1 responses are dominated by IFN- production
and a phagocytic cell response.• CD4 Th2 responses are dominated by IL-4 production and
the stimulation of an "allergic" type response.• The class of the response may be important to rid
particular kinds of infections.
Chapter 6
CD8killer
CD8 CD4
CD4Th1
CD4Th2
naive
effectors
Activation, proliferation, differentiation
Diverse outcomes of immune activation of mature T cells
Th1 vs Th2 is defined by distinctive pattern of cytokine expression
1 1
2
inappropriateactivation
leads to cell inactivation
inappropriateactivation
leads to cell inactivation
CD8 CD4
How are these cell fate decisions made?
Promotes homing to lymph nodes Promotes homing
to inflamed tissues
Effector T cells have altered homing properties
• Innate immune cells are key antigen presenting cells.Dendritic cellsMacrophages
• Cell:cell contact dependent signals are important for naïve T cell activation.
MHC+peptideB7 molecules
• Cytokines produced by antigen presenting cells and other innate immune cells can direct the character of the immune response.
IL-12IFN-IL-4
• T cell derived contact signals and cytokines can direct many other cell functions.
CD40LIL-4IFN-
Regulation of the class of the T helper response
Macrophage activation and stimulation of C’ fixing Ig isotypes
Class switch to neutralizing and mast-cell binding
isotypes (IgE). Activation of eosinophils
The Th1 pathway is the response to microbes that infect or activate macrophages and to those that activate NK cells
The Th2 pathway is the response to helminths (worms) and allergens (?) [associated with little macrophage activation]
TH0
Pleiotropy—n.The control by a single protein of several distinct and