Hypersensitivity Flashcards
- What can activation of the immune system lead to?
– Define ‘antigen’
- What does IgG3 potently activate?
Inflammation causing pain and discomfort
Any molecule or molecular structure that can be recognised by an antibody or the adaptive immune system Complement Fc receptor mediated phagocytosis
- Can IgA cross the mucosal epithelium?
- What does IgE induce?
yes
Mast cell degranulation
- What is another name for type I hypersensitivity?
- What is type I hypersensitivity?
Immediate or anaphylactic hypersensitivity
Allergic reaction provoked by re-exposure to a specific type of antigen referred to as an allergen
- What are type 1 responses mediated by?
- When do non-allergic individuals make IgE?
- When do allergic individuals make antibodies?
Antigen specific IgE antibodies
Response to parasitic infections or very potent venoms Produce it against common multivalent environmental antigens (known as allergens)
- Outline the process of type I hypersensitivity?
Generation of CD4 T cells and B cell helper follicular CD4 T cells which produce the type 2 cytokines IL-4 and IL-13
When these act on B cells they can promote B cell to switch to producing antigen specific IgE IgE bound to surface of innate immune cells (mast cells and basophils) If allergen encountered by cell bound IgE it results in rapid crosslinking and degranulation of the mast cell or basophil.
- Which granulocytic cells are involved in type I hypersensitivity?
- What is the name of the high affinity IgE receptor these granulocytic cells express?
- What are the end products of type I hypersensitivity reactions?
Mast cells and basophils
Fc epsilon receptor I Histamine, a host of cytokines that can recruit other cells and promote further Th2 differentiation Highly active smooth muscle contracting molecules such as leukotrienes and prostaglandins.
- Name and explain the 3 phases that occur due to the variety of molecules released during type I responses
Early phase - mast cells producing small bioactive molecules (in minutes)
Later response - early inflammatory cells (neutrophils) recruited (in hours) Late response - high frequencies of eosinophils are recruited and Th2 cells are present (3-4 days after exposure)
- What is another name for type II hypersensitivity?
- Give examples of type II hypersensitivity?
Antibody-mediated cytotoxic hypersensitivity
Immune thrombocytopenia Haemolytic diseases of newborns Graves disease
- What is graves disease?
Patients develop thyroid stimulating antibodies that bind the thyrotropin receptor resulting in secretion of thyroid hormones.
- What can type II sensitisation involve?
- what three responses can IgG and IgM result in?
Exposure to a foreign antigen
Aberrant response to a self-antigen resulting in IgGs or IgMs that recognise cell surface structures
- Anti-receptor activity – blocking or activating its function
- Antibody Dependent Cell-mediated Cytotoxicity (abbreviated to ADCC)
- Classical activation of the complement cascade
- What is the complement cascade?
- What effects can the complement cascade form?
Process in which antibodies on cell surface are recognised by the complement components
leading to the formation of the membrane attack complex (MAC) on the cell surface
cell death due to loss of osmotic integrity
MAC in surface of the cell, Inflammation, Opsonisation , Recruitment and activation of immune cells
- What are Fc receptors expressed by?
- What are antigen-antibody complexes in ADCC bound by?
- What does ADCC lead to?
Granulocytes and NK cells
Fc receptors (the constant tail regions of IgM and IgG antibodies bind to them, causing them to bring about an effect on the body)
Directed lysis of target cell
release of inflammatory mediators, chemokines and cytokines
- List some things type II hypersensitivity can result in?
Local/systemic inflammation
Cell depletion leading to a loss of function Imbalance in organ function
- What are immune complexes?
- If immune complexes aren’t efficiently cleared by the immune system where do they go?
- What symptoms can immune complexes not being efficiently cleared lead to?
Non-cell-bound antigen-antibody complexes which are normally cleared through the activity of the immune system
Deposited in blood vessel walls and tissues, promoting inflammation and tissue damage
Symptoms such as fever, rashes, joint pain or protein in the urine
- What are the terms for immune complexes being deposited in the blood vessels, kidneys and joints respectively?
- List 3 auto-immune diseases which involve type III reactions
- In which auto-immune disease do patients develop IgGs against DNA or proteins present in the nucleus (nucleoproteins) forming persistent immune complex deposits and a variety of pathologies?
Vasculitis , Glomerulonephritis, Arthritis
Rheumatoid arthritis, Multiple sclerosis, Systemic lupus erythematosus (SLE)
Systemic lupus erythematosus
