This document discusses cytokines, which are low molecular weight proteins that act as chemical messengers and influence the actions of immune cells. Cytokines can act in an autocrine, paracrine, or endocrine manner and have pleiotropic effects. They bind to receptor proteins on target cells and trigger intracellular signaling cascades that regulate gene expression. Examples of cytokines involved in hematopoiesis and the innate and adaptive immune response are provided.

1. Principles of Immunology
Cytokines
2/2/06
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Anonymous

2. Word List
 Autocrine
 Endocrine
 Immunoglobulin superfamily
 Interleukin
 Paracrine
 Pleiotropy
 Stem cell factor

3. Chemical Structure
 Low molecular weight proteins,
<30kD
 High affinity for receptors
 Active in picomole amounts

4. Chain of Cytokine Action
Stimulus>Cytokine-producing cell>
Cytokine>Target cell>Receptor>
Biological effect(s)

6. Names of Cytokines
 Source
 e.g.,Lymphokines
 Function
 e.g.,Chemokines
 Intercellular action
 e.g., Interleukins

7. Action of Cytokines
 Autocrine
 Affects the generating cell (self)
 Paracrine
 Affects cells in the immediate vicinity
 Endocrine
 Affects cells remote from the secreting
cell

9. Action of Cytokines
 Pleiotropy
 Affects multiple cell types
 Redundancy
 Multiple cytokines affects cells of the same type
 Synergy
 Cytokines acting in concert on the same cell
 Antagonism
 Competing actions
 Cascading
 Cytokines acting sequentially

12. Cytokine-generating Cells
 Innate immunity
 Macrophages
 Endothelial cells
 Fibroblasts
 Adaptive immunity
 T lymphocytes
 Macrophages
 NK cells

14. Cytokine Receptors
 Ig super family
 Class I- hematopoietin
 Class II-interferon
 TNF
 Chemokine

19. Cytokine Receptors
 Multimeric receptors
 Common signal-transducing subunits
 Unique high affinity subunits
 High affinity subunits associated with
activation of target cell

20. Signal Transduction
 Initiated by cytokine binding
 Activates JAK (Janus kinase)
 Phosphorylation of tyrosine
 Binding of STAT(Signal transducers
and activators of transcription)
 Translocation of STAT to cell’s DNA
 Transcription of specific target genes

22. Role of Cytokines in
Hematopoiesis
 SCF (Stem cell factor)
 GM-CSF (Granulocyte-macrophage
colony-stimulating factor)
 IL-3 (Interleukin 3)
 IL-5 (Interleukin 5)
 IL-7 (Interleukin 7)
 IL-11(Interleukin 11)

24. Cytokines in the Immune Response
 Innate immune response
 IL 1-(Macrophage)-fever, capillary effects
 IL 6-(Macrophage)-adaptive immunity via B cells
 IL 12(Macrophage)-adaptive immunity via T
helper cells
 TNF (Macrophage)-capillary effects, activates
neutrophils
 IFN alpha (Macrophage)-multiple effects
 IFN beta (Fibroblasts)-multiple effects

25. Cytokines in the Immune Response
 Adaptive immune response
 IL 2-(T cells)-multiple effects)
 IL 4-(T cells & mast cells)-T cell
differentiation, IgE production
 TGF beta –(T cells, macrophages)-
inhibits adaptive immune response
 IFN gamma-(T cells, NK cells)-
Macrophage activation

27. Subsets of T helper Cells
 T helper 1
 IgG production/Complement fixation
 Macrophage activation
 DTH
 CTL production
 T helper 2
 IgE production
 Eosinophils

29.  Cytokine antagonism and viral
diseases
 Using cytokines therapeutically