11 - IMMUNE SYSTEM PATHOLOGY Flashcards
Pathologies of immune system
Hypersensitivity reactions
Autoimmune disorders
Immunodeficiencies
DESCRIPTION: antigen
substance triggering immune reaction
Description: antibodies
specific binding to antigen facilitate phagocytosis
Descripton: B cells
produces antibodies
Function macrophages
Phagocytosis
Description of cytotoxic T cells (CD8)
immune cell destroying infected cells (viruses) & cancer cells
Description: Helper T cells CD4
boost activity of B cells & macrophages
Description: Dendritic cells
antigen presentation
fct neutrophils
kill bacteria, do phagocytosis & degranulation
Description complement system
set of plasma protein: inflammation, kill cells, facilitate phagocytosis
Description mast cells
release histamine, trigger inflammation
Definition of hypersensitivity
disproportionate reactivity to antigen
Definition of hypersensitivity reactions
immune responses to harmless antigens causing symptoms upon re-exposure
Definition of hypersensitivity disease
persistent & recurrent reaction to innocuous antigen
Type 1 HS: features
Mediated by Ig E antibodies triggering mast cells
Immediate hypersensitivity: response within minutes
Many allergic reactions: reaction to common environmental allergens
Harmless substances that can be:
- Inhaled: pollen, dust misters
- Injected: venom from bees or wasps
- Contact allergies: metals, latex
- Eaten: nuts, shellfish
type 1 HS: 2 steps reactions
1) First exposure = sensitization
Dendritic cell bring allergen to lymph nodes & show it to T helper cells
IL-4: stimulate B cells to produce antibodies (IgE)
IgE antibodies binds to mast cells (airways, GI tract, dermis)
2) Subsequent exposure
Allergen bind to mast cells: degranulation
* Release of pro-inflammatory mediators (histamine)
* Bronchospasm
* Vasodilation & increase permeability
Type 1 hs: symptoms (mild & other)
Mild symptoms
Urticaria
Asthma
Eczema
Allergic rhinitis: most common 10-30% of population globally
Other symptoms
Runny or stuffy nose
Sneezing
Red, itchy & watery eyes
Swelling around eyes
Anaphylaxis: type of HS, def & causes
Type 1
Definition
= life-threatening emergency & requires immediate intervention with injected epinephrine to restore blood pressure, strengthen heartbeat & open airways
Exposure to large quantity of allergen
Wide spread release of histamine: increase vasodilation + airways constriction
Not enough oxygen to vital organs
Causes
Insect bites & stings (ants, bees)
Food ingestion (peanuts, seafood)
Medication (penicillin, aspirin)
Type 1 HS: treatment
Anti-histamines: counteract histamine effects
Corticosteroids: reduce inflammation
Epinephrine: induces vasoconstriction (prevent anaphylactic shock)
Type 2 HS: 2 types
Cytotoxic hypersensitivity
Myasthenia gravis
Cytotoxic hypersensitivity type 2 : def, features & steps
Definition
= antibody mediated destruction of healthy cells
Features
IgG antibodies recognize cell surface or matrix antigens
Tissue specific
Timing: 2-24h
Steps
1) Phagocytosis
2) Activation of complement system
- Recruitment of neutrophils & degranulation
- Lytic death of host cells
3) Cellular dysfunction
Myasthenia gravis: type of HS, def, symptoms & def of myasthenia crisis
Type 2
Definition
= antibody directed against nicotinic receptors
Nerve impulse of motor neuron fail to pass neuromuscular junction & stimulate contraction
Fluctuating weakness & fatiguability of skeletal muscle (cranial muscles = first affected)
85% of patients generalized weakness affecting muscles of limbs (later onset)
= slow progressive disease with daily & longer term fluctuations in symptoms
Infections can lead to exacerbation of symptoms
Symptoms
Double vision & dropping eyelid
Fatigue while chewing
Open jaw
Difficulty swallowing
Trouble talking & walking
Myasthenia crisis
= life-threatening medical emergency due to weakening of respiratory muscles & requiring ventilatory assistance
Type 3 HS: 2 types
Cytotoxic hypersensitivity
Systemic lupus erythematous
Cytotoxic hypersensitivity type 3: def, features, An-Ab complex
Definition
= antibody mediated destruction of healthy cells
Features
IgG antibodies recognize soluble antigens
—> Formation of antigen-antibody complexes
Systemic
Timing: hours, days or even weeks
Antigen-antibody complexes
Less immunogenicity, difficult to trigger phagocytosis
Deposit on basal lamina of blood vessel
Activation of complement system
—> Inflammation: edema
—> Recruit neutrophils: degranulation & tissue damage
Results: vascular is
Most happening in skin, kidneys, joints, pleura & pericardium