# Cytokines These interactions involve **chemical mediators** - **Cytokines:** Proteins secreted by cells that act locally to change the behavior of neighboring cells by binding to specific receptors. - Cytokines made by [[The Lymphatic System]] are often called **interleukins** (IL) - **Chemokines** > [!quote] "All chemokines are cytokines, but not all cytokines are chemokines." Chemokines are a large and diverse group of chemical mediators There are five major classes of cytokines: - *Interferons (IFN)* - *Chemokines* - *Tumor Necrosis Factors (TNFs)* - *Lymphotoxins (LTs)* - *Interleukins (ILs)* In terms of [[cellular communication]], the term signaling is used for the creation **and** secretion of cytokines ## Opsonization > The word *opsonization* comes from an old Greek word for a delicious side dish; when a pathogen is **opsonized** it is **made more delicious.** ## Interferons (IFN) The type I group of interferons includes interferon-$\alpha$ and interferon-$\beta$ - All nucleated cells are capable of making Type I IFNS The only Type II Interferon is INF-$\gamma$ - Activates macrophages - Causes [[Antibodies|isotype switching]] to produce more IgG1 antibodies (which are good opsonizers and further promote the effectiveness of macrophages) ## Interleukins (IL) | a | | | ---- | ---- | | IL a | | | | | IL-1$\beta$ - Secreted by macrophages in response to infection - Acts as a master regulator of the induced innate immune response **IL-2** - Produced by activated [[T-Cells]] that is crucial for the proliferation of activated T-Cells and the activation of the adaptive immune response **IL-10** - Secreted by [[Helper T-Cells|Treg]] cells to *suppress the inflammatory* responses of Th1 and Th17 cells