Cytokines Flashcards
Define Cytokines
LMW proteins produced by any cell, whose biological effect varies according to the cytokine and cell involved.
Typically these molecules signal certain cell populations to activate, divide or hone.
Exert effects by binding to specific receptors on target cells and act as autocrine, paracrine and endocrine messengers.
Synthesised in response to cell surface signals.
Types of cytokines
Interferons
- produced by virus infected cells
- Type 1 (a and b) Type 2 (y or immune interferon)
- IFNa = produced by leukocytes
- IFNb = fibroblasts
- IFNy = T cells
- All released in response to viral infection.
- Prevent viral replication and have anti tumour activity.
Inflammatory Cytokines
- Endogenous pyrogens
- TNFa, TNFb, IL1a and IL1b.
Lymphocyte derived Cytokines
- Regulate immune function.
- Intralukens, released by leukocytes.
IFNa and IFNb (Type 1 IFNs)
IFNa = leukocytes
IFNb = fibroblasts
released in response to viral infection
protect uninfected cells by inducing production of intracellular molecules that inhibitt viral RNA and DNA.
Also increase expression of MHC Class 1 = >Lysis of virally infected cells.
Also have anti proliferative function
Used in Heb b and c infections.
IFN y (Type 2 IFNs)
Produced by T cells
Stimulates NK cells
enhances T cell activity by increasing MHC Class 2 expression on antigen presenting cells
Activates Macs to destroy
inhibits endothelial cell growth increases adhesive molecule expression
TNFa
Pro inflammatory cytokine
Produced by Macs, NKs, nuts and ends cells
Increases phagocyte function
Enhances MHC1 expression -> anti tumor.
TNFb
Secreted by T cells
Increases synthesis of acute reactive proteins, systemic hypotension, reduced myocardial contractility and intravascular thrombosis
- Involved in acute septic response, tutor necrosis and cachexia in cancer
Interleukins
Stimulate proliferation of T and B cells.
Activate T and b cells, Macs and increase production of acute phase proteins
IL1 = PG release in hypothalamus = fever.
