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  #1  
Old 11-02-2012
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Immunology Treating Immunoglobulin with Pepsin

IgM immunoglobulins from an individual A having one type of antigens (proteins) are treated with pepsin. When the product of this reaction is added to individual B having other type of antigens, the antigens will be:
A. Precipitate
B. Agglutinate
C. Lysed
D. Phagocytosed
E. Unaffected
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Old 11-02-2012
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Try it frens.............this is important..............the same concept has already been asked in exam.
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Old 11-02-2012
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Quote:
Originally Posted by subbi View Post
IgM immunoglobulins from an individual A having one type of antigens (proteins) are treated with pepsin. When the product of this reaction is added to individual B having other type of antigens, the antigens will be:
A. Precipitate
B. Agglutinate
C. Lysed
D. Phagocytosed
E. Unaffected
I would choose E) Unaffected. If I understood right the question, you have an Ig M that is treated with pepsin, resulting in a big fragment Fab, that would be able to precipitate and agglutinate. But the epitopes are already bound to antigens (individual A); so if you put them in contact to other antigens (individual B), the epitopes couldn't bind because they are specific for the others antigens (from ind A). At least this is my logic for the moment. Waiting for the response
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E. Unaffected
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Old 11-02-2012
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E ??? Idiotype is all about this .. Isn't it ??
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Quote:
Originally Posted by Teona View Post
I would choose E) Unaffected. If I understood right the question, you have an Ig M that is treated with pepsin, resulting in a big fragment Fab, that would be able to precipitate and agglutinate. But the epitopes are already bound to antigens (individual A); so if you put them in contact to other antigens (individual B), the epitopes couldn't bind because they are specific for the others antigens (from ind A). At least this is my logic for the moment. Waiting for the response
@Teona............question mentions an individual A with one type of antigens, it's not given whether the IgM from that patient after treatment with pepsin reacts with his antigen.............think over fren.
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Old 11-02-2012
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but i think it still as E

THANKS
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Old 11-02-2012
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Quote:
Originally Posted by subbi View Post
IgM immunoglobulins from an individual A having one type of antigens (proteins) are treated with pepsin. When the product of this reaction is added to individual B having other type of antigens, the antigens will be:
A. Precipitate
B. Agglutinate
C. Lysed
D. Phagocytosed
E. Unaffected
What is the correct answer?
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Originally Posted by venky2600 View Post
but i think it still as E

THANKS

E is not the answer.
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Old 11-02-2012
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Quote:
Originally Posted by subbi View Post
E is not the answer.
Ok, thank you! I imagined that E was not the correct one, but can you tell us what is the correct answer?
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Quote:
Originally Posted by Teona View Post
Ok, thank you! I imagined that E was not the correct one, but can you tell us what is the correct answer?
Here we're treating IgM from individual A with pepsin and this product reacts with antigen from individual B...........since it is treated with pepsin, it will either precipitate (if it's a soluble antigen) or agglutinate (if it's a particulate antigen)............but both answers are in option...................Kaplan says that in such case, student should assume that the antigen is soluble and that treatment would result in precipitation, not agglutination.................hence the answer is AA.............thanx.
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Old 11-02-2012
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I have a doubt..
Is it like a rule in general that the immunoglobulins treated with Pepsin Or papain react with any other antigen losing its antigen specifity ?? ..
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Quote:
Originally Posted by alice View Post
I have a doubt..
Is it like a rule in general that the immunoglobulins treated with Pepsin Or papain react with any other antigen losing its antigen specifity ?? ..

Yes, alice..........the assumption to soluble antigen is a rule...........also in such question where you're adding Ig to different person, we should assume that they reacted (though not mentioned in the book as rule)................You can refer to Kaplan Micro Pg. 86 Q. No. 2 which is a very similar question where IgM from person with group A antigen is reacting with group B antigen but in the same person here.....................
I don't think I have understood this stuff fully but this is a past question...........
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