Immunology 1: Tolerance and Autoimmunity Flashcards
Location for POSITIVE T cell selection? What is selected for/against?
Cortex of Thymus
Pre-T cells develop into double + cells and interact with MHC I & II molecules, those with moderate affinity progress, others die.
Location for NEGATIVE T cell selection? What is selected for/against?
Medulla of Thymus
The AIRE gene is responsible for what?
In T cell maturation if the AIRE gene is defective then auto reactive T cells are not induced to apoptosis.
Defect in AIRE gene leads to which syndrome?
Autoimmune polyendocrine syndrome
Where to Treg cells come from? What controls their development (2 things).
Treg cells are CD4+ cells that recognize self antigens but are allowed to develop into CD25+ cells.
Controlled by Foxp3 which is induced by TFGb
What is the function of Treg cells?
Regulate self-reactive lymphocytes (TH1, TH2, TH17) by secreting TGFb and IL-10.
Also down regulates B7 on dendritic cells.
How is anergy induced in T cells
T cells are inactive by interacting with an antigen presented by an APC lacking the B7 co-stimulator (caused by IL-10).
Mutations in HLA-B27 can lead to which disease?
Psoriasis, ankylosing spondylitis, IBS, Reiter’s syndrome
Mutations in HLA-DR2 can lead to which disease?
MS, SLE, Goodpasture syndrome, hayfever
Mutations in HLA-DR3/4 can lead to which disease?
Type 1 DM
Mutations in HLA-DR4 alone can lead to which disease?
Rheumatoid Arthritis
Disease caused by trauma to the eye and induction of self-reactive antigens.
Sympathetic Ophthalmia
Pernicious anemia
Caused by lack of IF secretion by Parietal Cells in stomach, results in decreased B12 absorption.
Sx:Assoication with H. pylori infection.
Triad of weakness, sore tongue, parasthesias
“Megaloblastic Madness”
3x rate of gastric adenocarcinoma
Dx: circulating antibodies to IF and other parietal cell components
Tx: B12
Goodpasture snydrome, anti-glomerular basement membrane (Anti-GBM) disease
Compliment fixing antibodies to Type IV collagen and attack lungs and kidneys basement membranes.
Sx: hemoptysis, pulmonary hemorrhage, malaise, chills, fever.
Dx: circulating anti-glomerular basement membrane antibodies. Kidney biopsy shows linear deposition of antibody and complement
Tx: Plasmapheresis of antibodies, immunosuppressive therapy, reduce lung irritants, ESRD - dialysis/transplant
Insulin-dependent diabetes mellitus type 1
Destruction of beta-cells in the islets of Langerhans of the pancreas. Development of ketoaidosis if insulin is withdrawn.
Sx: typically juvenile but can be 30/40’s. Hyperglycemia (<200 random). Peripheral neuropathy in glove/stocking pattern.
TH1 cells over-balance Treg cells and secrete IFNy which actives macrophages and Tc cells to kill the beta-cells. Beta-cells up regulate Fas during initial phases which allows FasL on Tc cells to target more easily.
Possible link to Coxsackie Virus (molecular mimicry with glutamic acid decarboxylase), also Rubella/Mumps.
HLA-DR3/4 link.
Tx: insulin, diet, excercise