DrVirgo
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After a full course of immunization with a new vaccine consisting of a recombinant polypeptide, 10% of adults fail to make antibody to the polypeptide. The nonresponders have an increased frequency of one HLA type. What is the most likely explanation for the failure of this group to respond to immunization?
A. Failure of B lymphocytes to recognize the polypeptide
B. Failure of T lymphocytes to recognize the polypeptide
C. Lack of Class I MHC Presentation of the polypeptide
D. Lack of Class II MHC Presentation of the polypeptide
Please explain the answer... Thanks. 
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| robin082006
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D?
lack cleass II MHC-->B cells cannot change to plasma cells--> no antibodies
what about B?
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| ts97
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D
I think B is wrong because helper T cells do not recognize polupeptides, they need this polypeptide to be presented to them as MHC II. In addition I think HLA is MHC II, am I wrong?
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| DrVirgo
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Robin, thanks for your answer.
I don't remember reading this in Kap Immuno... Where can i read more about this?
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| robin082006
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Virgo, Immulo is long, just read figures and tables. most questions of immuno can be answered if we memorized them.
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| tolito
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D.
it is not A cos even if Bcells do not recognise the protein and produce antibody to it directly (in T independent antibody production), the peptide can be processed via mhc 2 on APC to THelper which produces il4, and 5 that activate B cell and antibody will be produced ( T dependent antibody production).
CYTOTOXIC T cells CAN recognise peptides (viral envelope gycoproteins) presented on MHCI to them but this is cell mediated immunity and not humoral. no antibody is produced. rather, the activated Tcytotoxic produces perforins that perforate infected cell. remember this has to do with intracellular viruses.
MHC I is for cytotoxic cells which are not involved in humoral (antibody mediated ) immunity.
HLA A,B, C are associated with MHC I while HLA DP, DQ, DR are associated with MHC II.
You can get simple and clear immunology from medical microbiology and immunology. easier to understand than to memorise is my opinion.
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| tolito
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a little clarification.
polysacharides do not bind to class II MHC.
peptides are recgonised by MHC II
B cells recognise a wide range of antigens which incl bacterial capsular polysacch, DNA, RNA, and lipids. leading to T cell independent antibody production.
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| Cedrick
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Yes I read it too
D
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| bangledoc
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