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Old 06-17-2011
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Question Immunology - Antigen processing and presentation

Exogenous pathway of binding peptides to MHC-II is used to activate TH cells whereas Endogenous pathway is used for cytotoxic T-cells.

However, if we do have an INTRACELLULAR pathogen (eg: listeria - as kaplan mentions-) , activation of TH0 into TH1 cells occur !! My question is why does that happen ? Why not use the endogenous pathway and activate the cytotoxic t-cells instead of the helper cells ?

What am i missing ?
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Old 06-17-2011
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you need the t helper cells to actiavte the macrphages thereby destroying the intracellular organism.
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Old 06-17-2011
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Th1 lymphocytes are CD4+ Helper cells that enhance Cell mediated immunity vs Th2 Lymphocytes that enhance Humoral immunity
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Old 01-24-2012
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as I understand ,, intracellular pathogens stimulate Innate Immunity "strongly" causing release of IL-12 and IFN -GAMMA from Macrophages and Natural killer cells which stimulate differentiation of TH cells into TH-1 cells ,, that bind with infected cell inducing cell mediated immunity via cytotoxic t cells more macropkages and NK cell ,,,
Clinical correlation on that the difference between tuberculoid Leprosy and lepromatous Leprosy ,,,
it's well explained in cell mediated immunity chapter in kaplan Immunology ,,,
Good luck ,, and please correct me if anything wrong
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