Immunology Flashcards
What does pleiotropism mean in terms of cytokines?
Where one cytokine has multiple functions and actions
What does redundancy mean in terms of cytokines?
Where multiple different cytokines can all have the same function
What does synergy mean in terms of cytokines?
Where cytokines of redundant can act together to enhance a function, than if they were to function individually
What are 3 types of cytokine receptors?
- Common cytokine / haemopoietin receptor
- Chemokine Receptor
- TNF Receptor
What are the main types of TNF receptors?
CD40/CD154 - Induce gene transcription and role between T cells + APCs
Fas - induces apoptosis in target cels
TNF
What are features of a chemokine receptor?
Alpha-helices that span the cytoplasmic membrane 7 times → catalyse the replacement of GDP by GTP when bound to chemokine
What are features of common cytokine receptors?
Receptors for IL-2, IL-4, IL-7 consist of 3 polypeptide chain with common gamma chain
(game chain defective = x-linked SCID)
What are the 4 main cytokines involved in differentiating Naive CD4+ T cells into T cells
IL-4
IL-12
IL-6
TGFbeta
Name 3 pro-inflammatory cytokines?
IL-1b
TNF-alpha
IL-6
Name 3 anti-inflammatory cytokines?
TGF-b, IL-4, IL-10
What are the 5 main types of cytokines?
- Interleukins
- Tumour Necrosis Factor
- Interferons
- Colony Stimulating Factors
- Chemokines
What interleukin activates eosinophils?
IL-5
Which interleukins are mediators of allergy?
IL-4,5,6
Which interleukin is secreted by T helper 2 cells to promote Ig class switching in B cells?
IL-4
what interleukin is responsible for T cell proliferation and differentiation?
IL-2
What produces TNF-alpha
Macrophages and T helper 1 cells
When are interferons produced and what is the role of them?
Produced in response viral infections for destruction of viral RNA and protein synthesis
What are type II interferons?
IFN gamma
Activates macrophages and CD4+ Helper T cells
What are type 1 interferons?
INF-alpha and beta
Cause destruction of viral RNA, inhibition of protein synthesis and up regulation of MHC I for cytotoxic CD8 response
Procuded by viral infected cells and dendritic cells
What are colony stimulating factors?
Bind to surface receptors on haematopoietic stem cells in the bone marrow to proliferate and differentiate
- M-CSF (macrophage)
- G-CSF (granulocyte)
- GM-CSF (granulocyte/macrophage)
Which interleukin is a powerful chemokine of neutrophils?
IL-8
Which IL is over expressed by most tumours?
IL-6
(enhanced proliferation, angiogensis, invasiveness and metastasis)
What role does cytokines play in septic shock?
Over-production of pro-inflammatory cytokines = cytokine storm - commonly induced by viral infections
- Dilation of blood vessels, leakage of fluid into body tissues, pertubation of blood supply, tissue injury, widespread clotting, organ failure
- Symptoms - fever, circulatory collapse, DIC, haemorrhagic necrosis → multiple organ failure
What is the role of TNF-alpha in T2DM?
Over expression of TNF-alpha by adipose tissue of obese individuals = decreased cellular response to insulin and glucose uptake
What are risks of cytokine-based therapies?
Infusion reactions
Reduces cytokine activity → increased risk of infection and malignancy (Reactivate latent TB)
Pleiotropic action of cytokines → unpredictable and severe side effects
Very short half life → frequent administration
Why are blood levels of cytokines not measured?
They act over short distances - unable to pick up most levels in serum blood.
(Unless in occasions such as severe high levels such as septic shock - but can clinically see, so no need for tests)
What are the 4 Hypersensitivity Reactions?
ACID
1. Allergic
2. Cytotoxic
3. Immune complex
4. Delayed
What are the 2 phases in Type 1 hypersensitivity?
- Sensitisation Phase
(allergen picked up by dendritic cell - presented to T cell - matures into Th2 - secretes cytokines to induce B cell differentiation - make IgE specific to allergy - IgE bind to mast cell) - Allergy Phase
(Mast cell with IgE specific to allergen recognise allergen → allergen cross-links IgE → activation of mast cell = degranulation → histamines, leukotrienes, cytokines, prostaglandins → local and systemic symptoms of allergy)
What are the early and late allergic phases of asthma?
Early - mast cell degranulation -> bronchoconstriction, cell infiltrates, increased mucus
Late - chronic inflammation caused by chemokines