hypersensitivity Flashcards
triggers of hypersensitivity
- SELF ANTIGENS- autoimmunity 2. MICROBIAL ANTIGENS- excessive inflammation 3. ENVIRONMENTAL- allergy
persistent triggers of hypersensitivity can lead to
chronic disease
hypersensitivity
defect in regulation or targeting of the usually beneficial immune response
type I hypersensitivity
- immediate, IgE-mediated, allergy - within minutes - involve antigen specific IgE on effector cells - vasoactive mediators, lipid mediators, cytokine - HISTAMINE
examples of type I hypersensitivity
- allergic rhinitis (hay fever) - atopic asthma - anaphylaxis (food allergy, stinging insect allergy, drug allergy)
type I, II, and III hypersensitivity similarities
mediated by antibodies
type II and III hypersensitivity involve which antibodies
IgG and IgM
Type II hypersensitivity
- injury related to antibody directly bing to target - minutes to hours - antigens are specific cells are extracellular matrix - local tissue/cell specific
Type III hypersensitivity
- injury related to immune complex deposition - antigens are present in circulation - systemic
which class of immunoglobulin is most abundant in the bloodstream?
IgG
IgG
- neutralization of microbes and toxins - most abundant in the bloodstream - opsonization of antigens for phagocytosis by macrophages and neutrophils - activation of the classical pathway of complement - neonatal immunity - activates NK cells
IgM
activation of the classical pathway of complement
IgA
- mucosal immunity - neutralizations of toxins
IgE
eosinophils and mast cell mediated defense against helminths
type II hypersensitivity mechanism
antibodies causing 1. opsonization/phagocytosis 2. complement/Fc receptor inflammation 3. receptor activation
goodpasture syndrome
- anti-glomelular basement membrane disease
- antibodies against basement membrane in kidney and lung
- fatigue, blood in the ling, bloody urine, kidney failure
idiopathic thrombocytopenic purpure (ITP)
- autoantibodies against platelets –> opsonization in the slpeen
normal
autoimmune hemolytic anemia
- autoantibodies against RBC membrane proteins
type II hypersensitivity
- antibody stimulates the receptor without hormone
- antibody inhibits binding of neurotransmitter to receptor
- antibody binds antigen and attracts neutrophils and or complement which leads to inflammation
- antibody coats outside of cells and then phagocytes come and eat them
acute rheumatic fever, pemphigus vulgaris, pernicious anemia are clinical examples of type I or type II hypersensitivities
II
timing of type III hypersensitivtiy
3-10 hours
immune complex mediated hypersensitivity
Type III
mechanism of Type III hypersensitivity
antibodies bind appropriate sized antigens and deposit in vessels or tissue cause complement/Fc receptor inflammation
- causes vaculitis
anti-diphtheria horse serum for diphtheria leading to fever, joint pain and symptoms with just horse serum; would take 1 week for onset od symptoms, subsequent injections decreased time of reaction is an exmaple of type I/II/III
type III hypersensitivity
systemic lupus erythematosus
- type III
- usually women
SOAP BRAIN MD
- serositis
- oral ulcers
- arthritis
- photosensitivity
- blood (low WBC, RBC, and platelets)
- renal
- anti-nuclear antibodies
- immunologic
- neuroligic
- malar rash
- discoid rash
poststreptococcal glomerulonephritis and polyarteritis nodosa are examples of type I/II/III/IV
III
type IV hypersensitivity timing
1-3 dyas
type IV mechanism
- t-cells either through cytokines (CD4) or direct cytotoxic killing (CD8) cuase injurt
type IV is mediated by t cells/antibodies
t cells
type IV is/is not transferrable by serum
is not
which of the following is a primary cytokine secreted by CD4+ t cells in type IV cytokine mediated hypersensitivity
IFN- gamma
TB test is a an example of TYPE I/II/III/IV
IV
poison ivy
- contact dermatitis
- low molecular weight and soluble so crosses cell membrane
- modifies intracellular skin proteins, presented on MHC I cells
- TYPE IV example
- In preparation for receiving a kidney transplant, a 32 y/o male is given rabbit-derived anti-thymocyte globulin (ATG). A little over 1 week after receiving his transplant, he develops fever, red rash and joint pain.
- What type of hypersensitivity does this represent?
»A) Type I
»B) Type II
»C) Type III
»D) Type IV
»C) Type III
- Minutes after beginning a laparoscopic cholecystectomy on a 45 y/o female, the anesthesiologist notes hypotension and dropping SaO2. Under the drape, a red rash is noted on the patient.
- What type of hypersensitivity does this represent?
»A) Type I
»B) Type II
»C) Type III
»D) Type IV
»A) Type I
- Over the past year, a 27 y/o male had 3 episodes of isolated hemoptysis and mildly progressive shortness of breath. He presented to the ED with the new concern for blood in his urine and was found to have antiglomerular basement antibodies.
- What type of hypersensitivity does this represent?
»A) Type I
»B) Type II
»C) Type III
»D) Type IV
»C) Type III
treatment options
steroids, epinephrine, plasmapheresis, steroids
