Question

in your own words please.

What is the role of cytokine signaling in both types of immune responses? In Trypanosoma cruzi infections, innate and adaptive immune responses occur. Which stages of infection in T. cruzi are responsible for stimulating innate, cell- mediated and humoral immunity? Be specific.

Answer 1

The immune system is divided as innate and adaptive immune system. Cytokines plays an important role in signaling in both type of immune response.

• Cytokines: Cytokines are peptides and glycoproteins which are secreted by immune cells. Cytokines provides signals which mediate and regulate immunity of the body. They act as mediators between cells. Cytokine are grouped based on their function, cell of secretion, or target of action. Cytokines binds to receptors of target cells and hence gives signal and triggers cell mediated pathways. Binding of cytokines may autocrine: cytokines binds to same cell receptors, endocrine: binds to target cell or Paracrine: binds to receptors of target cell in close proximity.
• Cytokines plays an important role in the innate immune system which involves TNF-α, IL-1, IL-10, IL-12, type I interferons (IFN-α and IFN-β), IFN-γ, and chemokines whereas adaptive immune system involves IL-2, IL-4, IL-5, TGF-β, IL-10 and IFN-γ cytokines.
•   TNF-α and IL 1 are secreted by macrophages is response of microbial infection. Both cytokines help in acute inflammation.
• IL10 is produced by activated macrophages. It inhibits the production of IFN-γ and helps to turn on immune response mediated by TH2cells.It also helps in inhibition of cytokine production and class II MHC molecule
• IL 12 helps to stimulate the production of IFN-γ , also enhances functions killer cells.
•   Chemokines are chemotactic cytokines ; their main function is give signal to leukocytes at the site of inflection.
• IL 2 is produced by T cells. It acts as a growth factor for T cells. It also promotes the growth of B cells and helps to activate NK cells and monocytes.
• IL 4 acts as growth factor for T helper cells which ultimately helps in the production of an antibody response. It enhances production of Ig ,IgE antibodies.
•   IL 5 is promotes the growth and differentiation of B cells and eosinophils.
• TGF-β is produced by T cells and many other cell types. It inhibits the proliferation of T cells and the activation of macrophages.
• T. cruzi is a blood sucking parasite which causes trypanosomiasis in humans called Chagas disease. The life cycle of T.cruzi starts from animal reservoir, mostly mammals. Through bug vector this parasite is infected to human body. In the body of vector this parasite goes into the epimastigote stage and reproduces asexually. After reproduction, these epimastigotes become infectious, such infectious T.cruzi are called as metacyclic trypomastigotes.