DrVirgo
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In a random quality-control test of 73 batches of H. influenzae vaccines administered nationwide, the FDA discovered two lots in which the capsular polysaccharide of Hemophilus was not covalently coupled to the Diptheria toxoid. Which of the following immunogenic responses would be predicted in children receiving one of these unusual vaccine lots?
A. They should produce a normal delayed-type hypersensitivity response to Hemophilus
B. They should produce an normal IgA response to Hemophilus
C. They should produce a normal IgG response to Hemophilus
D. They whould produce a normaal IgM response to Hemophilus
E. They should produce natural killer cell response to Hemophilus
F. They should produce no response to Hemophilus
I have the answer, which I will post later... This question stumped me...
I would like an explanation from anyone who has a grasp on this... PLEASE!!
WHY does Hemophilus capsule have to be covalently coupled to Diptheria toxoid i the first place???
Hib and dTaP are different vaccines, right?
Thanks. 
Edited by DrVirgo on 07/11/06 - 06:32 PM
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| DrVirgo
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Any guesses?
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| study_ing
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D.
the t cell part of the immunity stimulates isotype switching
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| study_ing
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i think we conjugate to the toxoid coz we wanna stimulate the T arm of the immunity
as H flu polysaccharide ag is defective
( me had got the q wrong too..dont worry)
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| DrVirgo
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Yes, it is D.
This is the explanation:
The function of covalently coupling the capsular polysaccharide of H. influ to diptheria toxoid in this common childhood vaccine is to involve T cells to assist in the production of antibodies against Hemophilus. T cells respond to processed peptides presented in the grove of MHC antigens on Ag presenting cells, an dare necessary for causing class swetching in B cells. Therefore, in the absence of T cell stimulation, B lymphocytes will make only IgM, and will be incapable of switching to other isotypes of immunoglobulin production.
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| study_ing
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| MRMAVERICK
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d
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| tolito
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correct. remeber the hemophilus capsule is POLYSACCHARIDE. this is not recognised by t cells. they recognise only peptides. B cells can recog the polysacch and that is why they can produce antibodies but only M. no memory cells will be generated. this is reason for covalently bimding it to protein in order for memory cells to be generated.
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