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  #1  
Old 12-20-2011
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Immunology Why no TB granuloma in AIDS patients!

In patients with AIDS, the failure to form granulomas in tissues infected by Mycobacterium tuberculosis is most likely due to which of the following?

(A) Clonal deletion of T lymphocytes reactive to mycobacterial antigens
(B) Decreased production of tumor necrosis factor-α by macrophages
(C) Inability of T lymphocytes to provide helper functions for B lymphocytes
(D) Inability of T lymphocytes to recruit and immobilize monocytes
(E) Poor phagocytic activity of macrophages

Post answers with reasoning
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  #2  
Old 12-20-2011
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(D) Inability of T lymphocytes to recruit and immobilize monocytes

coz there is no TH1 to produce INF gamma to activate macrophages to form granulomas i hope to hear the answer soon coz my exam in few days hehe
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Old 12-20-2011
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(C) Inability of T lymphocytes to provide helper functions for B lymphocytes

AIDS=CD4 cells lost=no cytokines to recruit cells=cant recruit macrophages=no TB granuloma

what say?
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Old 12-20-2011
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Answer is inability of T cells to recruit Monocytes
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ANS: D

because, the formation of granuloma is based on immune response to bacilli.
in HIV (and other immuno suppresd patients), immune response is either delayed or absent.

immune response is ability to attract monocytes and other inflammatory mediators to the site of primary infection, which is delayed or absent in immunosuppresed...!!
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Old 12-20-2011
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My answer is D...........!!!!!!!!!!
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Matched!!!
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Old 12-20-2011
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This is a classic pathology question. Very good one indeed.
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well... i would say a pretty classic one...

see again,
you are able to eliminate most of the options, but get struck with the two options... here in this case, option C and option D.

well the answer is "D"
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Old 12-20-2011
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Post the answer .

the answer is D ,
because , normally with TB granuloma , the first line that forms the granuloma are the macrophages , they phagocyte the bacteria , but can't process them to present the antigen to T cell , So , they recrute more macrophages to the infected site , to prevent the spread of the bacteria , and during this process , some of the macrophages fuse togethor , forming multnucleaed giant cells << this is how normally granuloma occur

In HIV , macrophages and T cells are the ones that are affected by the virus , but mainly the T cells .

the virus distry the macrophage that wants to process it ( Don't 4get it's an APC= antigen presenting cell) when it "presents " the virus to T cell , then the virus gets into the T cell destroying it , then because the cytotoxic T cells are not yet affected ( remember the virus didn't reach the lymphocyte proginator ( like the stem cells but make lympho ) , so the cytotoxic T cells , will increase , and help to retain the control to the body by attaking or lets say decreaing the amount of the T cells that are affected ( because they are active , I mean the virus ) .
then the virus will hide , and remain inactive , until an infection or anyother condition that will increase the alert of immune system . And in this time , cytotoxic T cells will not help , because the original ( proginator cells ) are affected now . and here we call it AIDS . So , by affecting T cells , macrophages are also affected , and so the answer is D .



Long story ha !!!
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