Self recognition, Tolerance and Hypersensitivity Flashcards
What does Dendritic cells do?
Process antigen material and present on cell surface of T cells
How do B-cells work?
make antibodies which circulate and bind to antigens which attrack phagocytosis by neutraphils and macrophages
How do T cells work?
Helper cells - used cytokines to help leukocytes eliminate antigen
Cytotoxic - killer cells, kills cells that are antigen presenting
What type of immunity is B and T cells?
B is humoural
T is cell mediated
How are T helper cells activated?
Antigen presenting cells costimulate with inactive cD4 t cells to activate it
How are Cytotoxic killer cells activated?
Virus infected body cell costimulates by IL-2 from helper cells with inactive CD8 to activate killer cell
What is tolerance?
Immune cell non-reactivity to antigens
What are the 3 types of tolerance?
Self, Neonatal and Acquired
What is self tolerance?
Tolerance to innate antigens
What is neonatal tolerance?
Antigents encountered within hours after birth
What is acquired tolerance?
Development of self tolerance and self recognition by mature b and t cells
What breakdown can cause autoimmune disease?
Immunological tolerance
What type of selections are in T cells of the thymus?
Negative and positive
When does selection of t cells occur?
After they emerge from the thymus and selection of b cell
What is an acquired tolerance?
Non reactivity to an antigen that should cause an immune response
What is a example of an acquired tolerance?
Failure of immune system to destroy sperm and eggs
Oral tolerance
What is type 1 hypersensitivity?
IgE mediated - degranulation of mast cells, allergic asthma and takes 30 min
What is type 2 hypersensitivity and time?
IgG mediated - cytotoxic raction, complement lysis - takes days for drug allergies
What is type 3 hypersensitivity and time?
IgG mediated - 6-8 hours - immune complex reaction that complements activation - allergic vasculitis
What is type 4 hypersensitivity?
T cell mediated takes 2-3 days, allergic skin contact, delayed type
What type of antigen and effector mechanism is type 1?
Soluble and mast cell activation
What type of antigen and effector mechanism is type 2?
Cell associated antigen/cell surface receptor, antibody alters signalling and FcR cells complement
What type of antigen and effector mechanism is type 3?
Soluble antigen and complements phagocytes
What type of antigen and effector mechanism is type 4?
Soluble antigents and macrophage activation, igE production and killer cells
What are a few general properties of allergens?
Small, soluble, long lasting, low dose of allergen, mucosal, protease, th2 immune
Which organs do type 1 mainly manifest?
Skin mucosa then Respiratory
How are type 1 IgE mediated?
Atopic diseases caused by individuals mount over zealous responses e.g dust allergens
What type of allergens activate PAR receptors?
Protease
What does mast cell granulation release?
Increased blood flow, increase mucus secretion, fluid secretion - puffy eyes , runny nose
What 5 reactions are IgE mediated?
Systematic anaphylaxis, Acute urticaria, Seasonal rhinoconjuctivities, asthma and food allergy
What IgE mediated reaction is caused in the upper airways?
Rhinitis
What IgE mediated reaction is caused in the lower airways?
Asthma
What can allergic Rhinitis and asthma cause?
Airway remodelling hyperplasia, fibrosis
What can Anaphylaxis do?
Direct route into blood stream, lowers BP and airway constriction
What mutants trigger cold induced urticaria?
NLP3
What can overly sensitive mechanotransduction induce?
Mast cell degranulation
What do Eosinophils do?
Mainly kill parasites by reacting towards opsonised parasites
How can you treat mediator actions?
Antihistamines and b-blockers
How can you treat chronic imflammatory reactions?
Corticosteroids
How can you treat Th2 responses?
Desensitisation therapy by injections
How can you treat IgE binding to mastcell?
Anti-IgE antibodies
What were IgE responses originally evolved to do?
Destroy helminth and pathogens
How is Chronic inflammation caused?
Mediated by IgE and by apoptosis of keratinocytes
What do Type 2 antibodies attach to?
Epitopes on self cells
What does Type 2 induce?
Activation of compliment
What does Type 2 result in?
Vasodilation and migration of phagocytic cells to the effected tissue
What do type 2 cells promote?
Activation of membrane attack complex
What does type 3 target?
Immune complex deposition on vessel walls causes arthritis, nephritis
What are type 3 receptors caused by?
Antigen (self or non-self) antibody complexes
What does type 3 promote?
Inflammatory response - local or systematic
What is a type 3 local response?
Individual immunised against an antigen of a high conc
What is a type 3 systematic response?
Antigen complexes may form systematically - promote wide inflammatory response
What is an e.g of type 3 systematic response?
Post infectious glomerulonephritis - antibody stuck in glomeruli of kidney and inflamed, could be due to infection
How does Type 4 work?
Antigen injected to tissue and processed by local antigen presenting cells, Th1 effector cell recognises and releases cytokines acting on vascular endothelium and recruits phagocytes to site
What are the 3 types of type 4 hypersensitivity?
Delayed type, Contact, Gluten sensitive enteropathy
What agent is related to contact dermititis?
Hapten
What cells does contact agent bind with to self proteins?
Langerhann cells
How does BCG type 4 work?
Injection of inactivated will cause localised response and indicated if individual has had before
What happens in coeliac disease?
Peptides produced from gluten dont bind to MHC molecules and enzyme modigied the peptides to bind, bound peptide activates gluten specific cells, T cells kill epithelia
