Hypersensitivity reactions Flashcards
Hypersensitivity reactions
Altered state of immune responsiveness causes excessive or inappropriate immune responses which lead to tissue damage
how are hypersensitivity reactions classified
Classified due to the mechanisms which underlie the tissue damage
which 3 hypersensitivity reactions are antibody mediated
TYPE 1,2,3
type 4 is cell mediated
type 1 hypersensitivity is referred to as allergic or immediate hypersensitivity
how long does it take
onset within minutes
what antibody is made is type 1 in response to house dust , drugs or pollen
IgE
an example of systemic and localised type 1
anaphylaxis
allergic rhinitis and asthma
allergic rhinitis
type 1
when allergen like pollen or dust irritates the nose causing cold like symptoms such as stuffy or runny nose, sneezing and mucus and cough
pulmonary oedema
excess fluid in the lungs
eosinophilia
condition of having an increase number of eosinophils in the peripheral blood causing a rash, itching and asthma and diarrhoea
IgE is formed as a result of prior sensitisation ( previous contact with antigen) so coats mast cells and basophils
so when subsequent accounted with antigen what happens
IgE antibodies binding( cross linking with more of the same antibodies) cause degranulation of mast cells and basophils which release chemokine and cytokines causing various effects
Release of histamine and other mediators (e.g., prostaglandin, platelet-activating factor, leukotrienes, heparin, tryptase)
Type 2 is referred to as cytotoxic hypersensitivity how long does it take
minutes to hours
what antibodies are involved in type 2
IgG or IgM
summary of 5 mechanism involved
Complement-mediated lysis (MAC)
Complement activation and Fc-mediated immune cell activation
Opsonization → phagocytosis
Antibody-dependent cell-mediated cytotoxicity (NK cells)
Inhibition or activation of downstream signalling pathways
graves disease what is the target antigen
type 2
TSH receptors
hyperthyroidism
myasthenia graves what is the target antigen and what type
type 2
ACHreceptor
acute rheumatic fever what type and symptoms
type 2
myocardial antigen causing inflammation
myocarditis and arthritis
exogenous antigens
antigens that have entered from the outside of the Body by inhalation or indigestion - by endocytosis or phagocytosis
endogenous antigens
signals produced within your body own cells ( virus)
in type 3 what type of antigen does the antibody attack?
soluble one ( immune complex)
where in blood vessels do immune complexes get deposited in type 3
basement membrane then activate complement
in type 3 complement ystemis activated causing release of what
Causes release of anaphylatoxins which increase vascular permeability
(oedema)
Chemokinesis attracts neutrophils - degranulation - inflammation
(vasculitis)
type 3 is also known as immune complex hypersensitivity when iso set usually occur
2-6 hours
in type 3 can the antigens be exogenous or endogenous
both
systemic lupus erythrmatosus
type 3
what is lupus
conditions that affects immune system - causing joint pain, extreme tiredness and rash on your face
Polyarteritis nodosa
Hepatitis B virus surface antigen
casues vascultiies and affects kidneys
sudden weight loss, loss od appetite , abdominal pain , excessive fatigue and muscle and joint aches
Postsreptococcal glomerulonephritis
Streptococcal cell wall antigens
kidney disease causing nephritis develops about 2 weeks after a skin or throat infection - main symptoms are blood in your Childs wee and swollen ankles and puff eyes
serum sickness
antigens in medications cause immune system to react - proteins from nonhuman sources
anything from Arthritis, vasculitis, nephritis
Type 4 inflammation also called the delayed type starts around 2-6 hours but when does it peak
24-42 hours
by what method does type 4 use to cause inflammation
T cell ignited inflammation
rheumatoid arthritis
type 4
autoimmune - collagen?
Inflammation mediated by Th1 and TH17 cytokines. Role of antibodies and immune complexes?
causes pain and aching and tenderness and swelling in joints - weight loss and tiredness
MS
type 4
protein antigens in myelin
Inflammation mediated by Th1 and TH17 cytokines.; myelin destruction by macrophages
causes waddling gait and walking on toes - muscle pain and stiffness and learning difficulties
type 1 diabetes
type 4
Antigens of pancreatic islet β cells (insulin, glutamic acid decarboxylase)
T cell-medicated inflammation: destruction of islet cells by CTLs
inflammatory bowel disease
type 4
ulcerative colitis and Crohn disease
Inflammation mediated by Th1 and TH17 cytokines.
abdominal cramps , diarrhea , fever and weight loss
psoriasis
type 4
red and crusty patches of skin covered with slivery scales - body makes to many skin cells
memory aid
ACID:
A – Allergic/Anaphylactic/Atopic (Type I);
C – Cytotoxic (Type II);
I – Immune complex deposition (Type III);
D – Delayed (Type IV)
type 1 is first and fast
type 2 is cytotoxic
type 3 means three thing stuck together - antibody - antigen and complement
type 4 is associated with the type 4 - T cells, transplant rejection , TB , skin tests and touching ( contact dermatitis)
On placement, the GP is seeing an elderly lady with Rheumatoid arthritis. The GP explains that Rheumatoid factor is an IgM antibody that binds to IgG antibodies as an antigen. This immune complex travels in the blood and deposits in joints, which activates the complement system and leads to chronic inflammation.
The GP tests you by asking what type of hypersensitivity reactions is this?
Type 3
peumonia can be causes by streptococcus and is normally found CAP. Staphloccuys can also be an agent where is this found
HAP
