Anergy in T Cells

[blazinfury]

I understand the idea of how anergy happens but I cannot find a clear explanation for why it happens and why there is no co-stimulation? What regulatory mechanism is preventing the B7 and CD28 receptors from interacting? I ask because at least in the thymus, the T cells are in an isolated and controlled environment and they have a hard time leaving if they have receptors against self. However, the peripheral tissues are like an open area. So what is the regulation that is occurring there?

[Vexen]

"In order to prevent this process, lymphocytes possess an intrinsic quality-control mechanism. This machinery shuts down the lymphocytes' ability to expand, if the trigger for the expansion turns out to be the body's own protein. T-cell anergy can arise when the T-cell does not receive appropriate co-stimulation in the presence of specific antigen recognition. B-cell anergy can be induced by exposure to soluble circulating antigen, and is often marked by a downregulation of surface IgM expression and partial blockade of intracellular signaling pathways."

"In order to prevent this process, lymphocytes possess an intrinsic quality-control mechanism. This machinery shuts down the lymphocytes' ability to expand, if the trigger for the expansion turns out to be the body's own protein. T-cell anergy can arise when the T-cell does not receive appropriate co-stimulation in the presence of specific antigen recognition. B-cell anergy can be induced by exposure to soluble circulating antigen, and is often marked by a downregulation of surface IgM expression and partial blockade of intracellular signaling pathways."

[animodel123]

Here is an article that might help you understand: T cell anergy is a tolerance mechanism in which the lymphocyte is intrinsically functionally inactivated following an antigen encounter, but remains alive for an extended period of time in a hyporesponsive state. Models of T cell anergy affecting both CD4+ and CD8+ cells fall into two broad categories. One, clonal anergy, is principally a growth arrest state, whereas the other, adaptive tolerance or in vivo anergy, represents a more generalized inhibition of proliferation and effector functions.......

[Xalatan]

CTLA-4 provides the regulatory mechanism that counteracts B7 and CD28 interaction. CD-4 cells express both CTLA-4 and CD28. B7-CD28 provides the co-stimulatory second signal for T cell activation, but B7-CTLA4 leads to anergy and tolerance in the Th cells.

Mutations in CTLA4 causes autoimmune diseases such as IDDM, Grave's, Hashimoto's, Coeliac's, SLE.