Bela
Forum Guru
Topics: 76
Posts: 412
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Guys, can someone tell me shortly the differences between the 4 types of hypersensitivity. Actually, I'm more interested in Type 2 and 3. I always had them memorized but to be quite honest, this lecture sucked and I was never able to fully understand how you categorize these diseases. I mean, let's say they give you a disease, how would you know which type of hypersensitivity goes under other than memorizing them? (always referring to type 2&3).
Thnx! And oh, please, don't just reiterate the book cuz it won't help me 
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| jayesh
Forum Junior
Topics: 2
Posts: 46
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type1 HS IgE mediated and it is immediate
type 4 is delayed type, T lymphocyte mediated
type 2 is antibody against any cells, receptors etc...
if they destruct that cell or tissue then it is cytotoxic
if they dont destruct, but alters the function of that cell/ receptor then it is non cytotoxic
ex in ITP (idipathic thrombocytopenic purpura) Ab against platelets are formed , so they destruct platelet so it is type 2. cytotoxic
in Myasthenis gravis Ab is against Ach receptors ...they #the receptors and inhibits NMT . the receptors r not destructed ...so it is non cytotoxic
type 3 is immune complex mediated i.e Ag.Ab complex
the difference with type 2 is, this complex is circulating andgets deposited anywhere ...so they have more systemic feature
hope u r clear now
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| KEROCHI
Forum Guru
Topics: 60
Posts: 971
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my code for this types of HYPERSENSITIVITY RXNS.
Type 1- A
Type 11- C
Type 111- I
Type 1V- D
= ACID
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| KEROCHI
Forum Guru
Topics: 60
Posts: 971
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What is the diff. b/n atopic dermatitis & contact dermatitis, clinically & mechanism wise?
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| ssrpk
Forum Fanatic
Topics: 154
Posts: 2,819
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well atopic dermatitis will be immediate reaction to an antigen while contact one will be mediated by DTH!
in contact dermatitis there will be induration tht will be particularly evident at the pont of exposure, consider PPD skin test!
while atopic will be characterized by hives with edema and erythema etc.!
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| hgy
Forum Newbie
Topics: 0
Posts: 22
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What's penicillin allergy, Type I or Type III?
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| CampNou
Forum Junior
Topics: 0
Posts: 33
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Well in the case of penicillin, I believe that the Rash is type I Hypersensitivity and the Hemolitic Anemia would be type II. Someone correct me here.
JC
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| paganini
Forum Senior
Topics: 26
Posts: 159
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To CampNou:
Actually Penicillin can produce more than one hypersensitivity reactions, you said two of them.
Type I: Anaphylaxis
Type II: Hemolytic anemia
Type III: Serum sickness
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| Palaniappan
Forum Senior
Topics: 30
Posts: 148
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Guys..Does serum sicknes share its clinical features with type 1 HS??I can sense that the only difference between the two is the time..The formewr occurs immediate..Can anybody explain a little bit more??(including arthus reaction)
Thanx
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| Clozapine
Forum Elite
Topics: 15
Posts: 167
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Yes... the basic difference is Anaphylaxis or type 1 HS is immediate onset type, b/c we all know, IgE`s are preformed and bound to mast cells and basophils awaiting secondary exposure.
But in serum sickness/type III HS
, it takes time for the body to produce antibodies to a new antigen, symptoms do not develop until 7 - 21 days after initial exposure to the antiserum. Patients may develop symptoms in 1 - 3 days even if they have previously been exposed to the offending agent. And ofcourse the type of antibodies are IgM or IgG(in case of previous exposure)
Additional sign symptoms in serum sickness are ~
Enlarged Lymph nodes ( they are actively making antibodies)
Fever
Joint pain (precipitation of Ag-Ab complexes in joints)
Hematuria (precipitation of Ag-Ab complexes in glomeruli)
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