Immune recognition and immune tolerance Flashcards
What are the two stages of thymic education of T cells
TCR genes are rearranged then put together
Cells with non-functional TCR die via apoptosis
Where does the positive selection part of thymic education occure in the thymus?
Thymic cortex
What are TMECs?
Thymic medullary epithelial cells in which negative selection takes place
What happens to lymphocytes in the thymic medullary epithelial cells?
Lymphocytes are tested here against self proteins, ones with low affinity are released into the bloodstream but ones with a very high affinity (which would cause autoimmune disease) are killed via apotosis (activation induced death)
What process fails in TMECs that leads to autoimmune disease?
TMECs need to have transcription factors that allow them to have TRAs (tissue restricted antigens, like insulin etc) if the TMECs don’t have these antigens then there will be an autoimmune disease
What are the peripheral mechanisms of immune tolerance that keeps T-cells behaving?
Anergy, and presence of Tregs
Describe the process of anergy
Signal 1 (TCR + MHC) without signal 2 (CD28 + CD86) in antigen recognition causes anergy. T-cells remain in circulation but is unresponsive to future stimulation.
What do Tregs do?
Stops T-cells from proliferating and from producing cytokines and reduces costimulation
What are n-Tregs?
Natural Tregs, produced in the thymus.
What are a-Tregs?
Adaptive Tregs, develop from naïve T cells in periphery; regulates responses to food antigens
Describe the development of a-Tregs
From naïve T cells in the periphery
