Hypersensetivity Reactions Flashcards
Which Hypersenstivity is Asthema?
Classic Type I reaction (HSR-1)
Asthema presentation- when complains are worse?
Cough worsed at night, in running in cold weather difficulty breathing (cold air + during sleep nerrow airways)
Which HSR all of this exmaple represent:
Asthema, food allergy, allergic rhinitis, anaphylactic, transfusion reaction (in IgA def pt).
HSR-1
most common cause of death from anaphylactic
bronchoconstriction
drug of choice for anaphylaxis
Epinephrine (Beta-2 agonist + alpha 1 activity)
whats the pathgenesis of HSR-1?
what heppens on first exposure?
what heppind on the second
1st exposure = no problem»_space; B cells present allergan to Th2»_space; Th2 secrete IL 4+13 > IgM to IgE»_space; IgE binds to Fc-epsilon on MAST + Esionophils
2nd exposure - Allergan bind to Vriable regions on IgE bound to MAST»_space; IgE brought togther from different MAST cells»_space; Degranulation»_space; Histamine, bradykinine, Heparin»_space; Vasodilation (Dec. SVR + BP = hypotension)»_space; Increasd vascular permeability»_space; Edema
When IL-5 is secreted to which class swithich IgM turn?
Igm»_space; IgA
when Th2 secreted IL 4+ 13 to which class switching IgM will turn?
IgM»_space; IgE
Whats the mechanism of action of Omalizumab?
Disrupt interaction between Fc-epsilon and constant region on IgE
24y pt with Hx SLE + jaundince + labs: Indirect hyperbilirubinemia + coombs positive. Whats the diagnosis? whice HSR is it?
Coombs positive autoimmune hemolytic anemia- Ab against RBC.
Type II hypersensetivity
how to remember all the 4 HSR reaction:
Mnemonic ACID:
A- allergic/ Anaphylaxic/ Atopic (type I)
C- Cytotoxic (type II) (Ab binds to antigens on healty cells)
I- Immune complex deposition (Type III)
D- delayed , ( type IV)
What causes HRS-II?
IgM + IgG binds to cells»_space; Activating CLASSIC complement cascade»_space; cells hemolysis
All of this are exmpales to which HSR? Mysthenia gravis, Acute hemolytic transfusion, Reumatic fever, Goodpasture synd?
Type II HSR
Whats the mechnism of type II HSR in Rheumatic fever?
molecular mimicry»_space; Ab against Strp. Pyogenes croos react with Antigens in Myocardium»_space; MS / MR, Joints»_space; joint pains , Basal ganglia»_space; Sydenham’s syndrome.
cross recativity
Whats the mechnism of type II HSR in Goodpasture synd?
Ab against type IV collagent in basment membraneturia»_space; biopsy of kidney - Linear Pattern on Immuo-Fluro. Ab against alvelolar in lungs: dyspnea, hemoptysis, cough
Which parts are being atteck in Goodpasture syndrome
Lungs
kidneys
anti-GBM
What is the HSR?
Pt recevies treament with RTX»_space; 6 days later: joint pain + urticarial pruritis rash + fever + weakness + low C3+ C4. whats the diagnosis?
HSR type III (immune complex)
Serum sickness (5-14 days) after exposure to foregin protein (vaccination, Ab, antitoxin)
