Hypersensetivity Reactions

Question 1

Which Hypersenstivity is Asthema?

Answer 1

Classic Type I reaction (HSR-1)

Question 2

Asthema presentation- when complains are worse?

Answer 2

Cough worsed at night, in running in cold weather difficulty breathing (cold air + during sleep nerrow airways)

Question 3

Which HSR all of this exmaple represent:
Asthema, food allergy, allergic rhinitis, anaphylactic, transfusion reaction (in IgA def pt).

Answer 3

HSR-1

Question 4

most common cause of death from anaphylactic

Answer 4

bronchoconstriction

Question 5

drug of choice for anaphylaxis

Answer 5

Epinephrine (Beta-2 agonist + alpha 1 activity)

Question 6

whats the pathgenesis of HSR-1?
what heppens on first exposure?
what heppind on the second

Answer 6

1st exposure = no problem&raquo_space; B cells present allergan to Th2&raquo_space; Th2 secrete IL 4+13 > IgM to IgE&raquo_space; IgE binds to Fc-epsilon on MAST + Esionophils

2nd exposure - Allergan bind to Vriable regions on IgE bound to MAST&raquo_space; IgE brought togther from different MAST cells&raquo_space; Degranulation&raquo_space; Histamine, bradykinine, Heparin&raquo_space; Vasodilation (Dec. SVR + BP = hypotension)&raquo_space; Increasd vascular permeability&raquo_space; Edema

Question 7

When IL-5 is secreted to which class swithich IgM turn?

Answer 7

Igm&raquo_space; IgA

Question 8

when Th2 secreted IL 4+ 13 to which class switching IgM will turn?

Answer 8

IgM&raquo_space; IgE

Question 9

Whats the mechanism of action of Omalizumab?

Answer 9

Disrupt interaction between Fc-epsilon and constant region on IgE

Question 10

24y pt with Hx SLE + jaundince + labs: Indirect hyperbilirubinemia + coombs positive. Whats the diagnosis? whice HSR is it?

Answer 10

Coombs positive autoimmune hemolytic anemia- Ab against RBC.
Type II hypersensetivity

Question 11

how to remember all the 4 HSR reaction:

Answer 11

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)

Question 12

What causes HRS-II?

Answer 12

IgM + IgG binds to cells&raquo_space; Activating CLASSIC complement cascade&raquo_space; cells hemolysis

Question 13

All of this are exmpales to which HSR? Mysthenia gravis, Acute hemolytic transfusion, Reumatic fever, Goodpasture synd?

Answer 13

Type II HSR

Question 14

Whats the mechnism of type II HSR in Rheumatic fever?

Answer 14

molecular mimicry&raquo_space; Ab against Strp. Pyogenes croos react with Antigens in Myocardium&raquo_space; MS / MR, Joints&raquo_space; joint pains , Basal ganglia&raquo_space; Sydenham’s syndrome.

cross recativity

Question 15

Whats the mechnism of type II HSR in Goodpasture synd?

Answer 15

Ab against type IV collagent in basment membraneturia&raquo_space; biopsy of kidney - Linear Pattern on Immuo-Fluro. Ab against alvelolar in lungs: dyspnea, hemoptysis, cough

Question 16

Which parts are being atteck in Goodpasture syndrome

Answer 16

Lungs
kidneys

anti-GBM

Question 17

What is the HSR?

Pt recevies treament with RTX&raquo_space; 6 days later: joint pain + urticarial pruritis rash + fever + weakness + low C3+ C4. whats the diagnosis?

Answer 17

HSR type III (immune complex)

Serum sickness (5-14 days) after exposure to foregin protein (vaccination, Ab, antitoxin)

Question 18

what the prognosis of Serum sickness?

Answer 18

Resolve spontenously over days

Question 19

mechanism of RTX? how reduce inflammatory?

Answer 19

Ab against CD20&raquo_space; kill B-cells&raquo_space; less inflammatory reaction

Question 20

why does the complement cascade is being activated in HSR type III?

Answer 20

beacuse of the Antigen-Antibody complexes that move around the body

Question 21

whats the pathogenesis of HSR-IV

Answer 21

allergan binds to antigen on skin&raquo_space; macrophages present on MHC II to CD4 (Th1)&raquo_space; CD4 release INF-gamma&raquo_space;activation of macrophages&raquo_space; phagocytes the antigen on the skin + release cytokines (IL1-IL6, TNF-a)