Evaluation – Questions & answers
Cite mechanisms that participate in the prevention of undesirable responses of the adaptive immune system.
Negative selection (or central tolerance), ignorance, peripheral tolerance by intrinsic (anergy) or extrinsic (Tregs) mechanisms.
Cite different mechanisms Tregs use to exert their suppressive functions.
T cell deprivation of interleukin-2 by high CD25 expression, production of inhibitory cytokines (IL-10, TGFb, IL-35) or other molecules (adenosine), down-regulation of dendritic cell functions, cell killing.
What are the main 3 conclusions of Sakaguchi’s 1995 experiment in which transfer of CD4+CD25- T cells to an alymphocytic host provoked multiple autoimmune diseases that were prevented by CD25+ T cell addback?
(1) a normal repertoire physiologically contains autoreactive T cells, (2) CD4+CD25+ T cells are a population of naturally occurring Tregs that control the activity of autoreactive T cells, and (3) Treg transfer might be used for therapy of autoimmune diseases.
What cytokine are Tregs critically dependent on?
interleukin-2 (IL-2)
What phenotype can identify blood Tregs in patients using flow cytometry?
CD4+ CD25hi ; CD4+ CD127-/lo ; CD4+ FOXP3+
