Endocrine Autoimmunity Flashcards
What is an autoimmune disease?
- involves an immune response or attack against a host organ
- includes Addison’s disease, Graves disease, type I diabetes, hashimto thyroiditis
What organs are sensitive to autoimmune attack?
- endocrine organs
- adrenals, gonads, pancreas, pituitary, thyroid
What are the two immune systems?
- humoral immune system
- cellular immune system
How do TCRs have diverse recognition possibilities?
- they are able to rearrange their DNA during development
- applies to B cell synthesis of Ab as well
How are potentially dangerous T and B cells that have self reactive receptors eliminated?
- by negative selection in the thymus and bone marrow
What presents surface T-cell receptors? What do they
- cytotoxic T cells
- develop T cell receptors that have antibody like molecules on their surface that display an Ab like recognition for specific pathogen
What are antigen presenting cells?
- after phagocytosis of foreign bodies, they process the foreign proteins and ten move these molecules to the surface with major histocompatibility (MHC class II receptors)
What are the steps in antigen recognition by T cells?
- antigen uptake
- antigen presentation: APCs deliver antigen specific signal
- T cell activation
- T cell inactivation
What occurs during T cell activation?
- required secon signal is provided via CD80/86 - CD28
- induces the expression of CD154 and and CD152
- T cell CD154 binds with CD40 on APCs
- these interactions induce activation and proliferation of downstream effector cells
How are T cells inactivated?
- CD152 will preferentially bind o CD80/86 on APCs
- displacing CD28
What happens if the molecular architecture is a fit?
- productive interaction
- TH cells activates to display more of this TCR
- TH cells activate B cells to differentiate into plasma cells and make antibodies
What do all cell types display on their surface?
- display Ag with MHC class I molecules
- formed from proteolytic degradation of endogenous protein
What are the two signals that T cells require to activate?
- TCR expressed antigen specific receptor binds to antigenic peptide held by MHC complex
- APC CD80/86 binds to T cell CD28
What does T cell activation lead to?
- T cell proliferation and increased release of IL-2 and expression of Bcl-xL
What are the steps in T cell tolerance in the thymus?
- pre-t cells rearrange their t cell receptor
- unproductive rearrangements lead to apoptosis
- productive pre-t cells are testes for self antigen recognition
- clonal deletion indicates elimination of cells with too high or no avidity for self antigen
- low-avidity cells reach the periphery as mature CD4 and CD8 cells
