Question

regulatory t cells (Treg) play important roles in autoimmunity and regulation of the mucosal immune response. Describe how Treg are generated within the immune system and their role in both autoimmunity and regulation of the mucosal immune reaponse.

Answer 1

T reg cells are the cells that have a role in regulating or suppressing other cells in the immune system.They control the immune responses against own cells so as to prevent autoimmune diseases.

Thesw cells are formed from the progenitor cells of the bone marrow. Theie formation starts as like other T cells as CD4-CD8-TCR- cells at the double-negative stage.They later rearrange its T cell receptor genes to form a unique, functional molecule, which are tested against cells in the thymic cortex for minimal interaction with own major histocompatibility complex.The selection of Tregs occurs on radio-resistant hematopoietically-derived MHC class II-expressing cells in the medulla or Hassal's corpuscles in the thymus.These cells under the double positive stage expresses Foxp3 under the interaction with thymus cells.TheT cells must recieve the correct amount of stimulation to become Treg cells otherwise they may either die or become effector cells.

The T regulatory cells prevent autoimmune responses of the body against our own cells.

They protect the body against the autoimmune responses by supressing the actionand regulation of mucosal immune response in many ways like,

• Production of inhibitory cytokines like Transforming growth factor beta,Interleukin 35 and Interleukin 10.
• By inducing apoptosis of effector cells,through the production of Granzyme B.(suppressor of the activation of effector T cells)
• induction of immunsuppressive indoleamine 2,3-dioxygenase.
• Through direct interactions with dendritic cells
• Through the IL-2 feedback loop.
• Also by the prevention of co-stimulation through CD28 on effector T cells by the action of the molecule CTLA-4.

These T regulator cells prevent the hyperactivity of the immune system in total and helps in maintaining an immune homoeostasis.