dr_bilalahmad
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29. 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
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| star1
Forum Guru
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D seem to be right...
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| sridevibandaru24
Forum Guru
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Yeah!D is right
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| Musuq
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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?
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| Musuq
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The MHC II molecules are present in all cells with the APC (Antigen Presenting Cell) feature like Macrophage, B lymphocyte, dendritic cells and Langerhans cells. The MHC II has a Peptide binding Groove which will contain part of the peptide from the antigen processed that we want to present to THo cell.
In this qs they tell us that 10% fail to make Ab to this new polipeptide vaccine, so this can tell us that TH2 switching have been affected because we have no AB produced; but at the same time these group who failed the humoral response has an increased in the expression of one HLA type, I think it might be the MHC I which is increased cause this has nothing to do with Humoral response.
What we need for the Humoral response is the TH to recognize the peptide on the MHC II, and if we have a lack of this MHC II, TH wont be able to recognize the peptide and thus wont activate TH2, so, no Humoral Response, no Antibodies would be made.
I had doubts with B) but, T lymphocyte (TH) doesn't recognize only the peptide, but the MHC II-Peptide complex, so I think D) is more specific.
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| Musuq
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just reviewing
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| NE
Forum Guru
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I guess B and D are right but the correct ans is D because in the stem q is something about the specific HLA; T lymph. need both MHCII and non self polypeptide recognition.
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| GardenGuy
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I go with D, T cell just recognizes peptide-Ag presented by APC, not free Ag.
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| qumsieh
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Yes, I agree, D) is the answer!
Ross University Graduate
Massachusetts General Hospital
Harvard College
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