Cytokines & Chemokines Flashcards
Describe cytokines.
-effective immune response poss when interaction w hematopoietic, lymphoid, & inflammatory cells is poss
-interaction between cells coordinated via proteins called cytokines
>low MW protein/glycoprotein made by lymphocytes
>OG ‘lymphokines/monokines’
>cytokines called interleukines (IL) bc made by & act on leukocytes
Describe chemokines.
-imp in communication of leukocytes
-recruit & activate leukocytes
Describe chemotaxis.
-cells move from area of low chemical signal to high
Describe the properties of cytokines.
-bind to receptor on target cells = initiate activating/suppressive signals
-cytokines = high affinity for receptors
>low conc initiate cytokine signaling
Describe the 3 ways a cytokine can bind to a receptor.
- Receptor located on same cell that made the cytokine & activate that cell = Autocrine
- Cytokine binds to receptor found on cell near the producer cell = paracrine
- Binds to receptor found on a distant cell = endocrine
Describe the 5 different types of cytokine actions.
*allow cytokines to regulate activity of immunocompetent cells in a coordinated way
*cytokines act in antigen nonspecific way (bind to any cell that express a receptor for that cytokine)
1. Pleiotropic = cytokine exerts diff effects on diff target cells
2. Redundant = 2 or more cytokines exert same effect on same cells
3. Synergistic = effect of 2 cytokines on cell is greater than additive effect of individual cytokines
4. Antagonistic = one cytokine inhibits effects of another
5. Cascade = action of cytokine leads to induction of 1 or more cytokines -> make more cytokines
Describe cytokines, hormones, & growth factors.
-all secreted that have effects at picomolar conc by binding to receptors
-expression is diff
>GF = expressed constitutively
>hormones & cytokines = expressed in resp to discrete stimuli
>cytokine secretion short lived
>hormones endocrine only & made by specialized glands where cytokines are made by diff cells & do endocrine, autocrine, paracrine
Describe the biological functions of cytokines.
-cell & humoral immunity
-induce inflammatory response
-regulate hematopoiesis
-regulate proliferation & differentiation of cells
-regulate intensity & duration of immune resp
-wound healing
Describe the different groups of proteins cytokines belong to.
-hematopoietins
-interferons
-chemokines
-TNF
Describe immunoglobulin superfamily receptors.
Describe class I cytokine receptors (hematopoietin).
Describe class II cytokine receptors (interferon).
First 4
Describe TNF receptors.
First 2
Describe the organization of cytokine receptor.
-most receptors are a few subunits
-one subunit is required for cytokine binding & second for signal transduction
-some receptors belong to class I receptor
-each subfamily of receptor has a identical signaling subunit but diff cytokine binding subunit
>GM-CSF = common B subunit
>IL6 = common gp130 subunit
>IL2 = common y subunit
Describe IL2 receptor.
-2 chains: a, B, y
-IL2R found in 3 diff forms of diff affinities to IL2
1. Monomeric IL2Ra = low affinity for IL2
2. Dimeric IL2RBy = intermediate affinity for IL2
3. Trimeric IL2RaBy = high affinity for IL2
Describe the structural organization of chemokines.
-4 conserved cysteins
>subgroups:
1. C chemokines - first 2 conserved cysteins bound by side disulphide bonds
2. CC chemokines - first 2 cysteins positioned one after another & each has a side chain
3. CXC chemokines - between 1st & 2nd conserved cysteins there is a X other than cystein
4. CX3C chemokines - 3 amino acids other than cystein are located in between the first 2 cysteins & there is a mucin domain
Describe chemokine receptor structure.
-extracellular domain for chemokine binding
-7 transmembrane domains
-intracellular domains a, B, y = associated w G protein
*name of receptor indicated type of chemokine that binds to that receptor
>EX: CR denotes receptor for C chemokines
>EX: CCR denotes receptor for CC chemokines
