macrophages vs. lymphocytes

[ctizzle13498]

ok so im confused. in viral mengitis and TB meningitis, the predominant cell type is lymphoctyes.

However, I just missed a question on NBME 11 that said, in a PPD test for TB, you will get predominantly macrophages.

How is this possible? I guess I am confused b/w when macrophages come and when lymphocytes come

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[1badvette]

does it have something to do with presensitized lymphocytes activating macrophages to the site .. PPD test is a delayed type 4 hypersensitivity ??

 

[Tig2575]

ok so im confused. in viral mengitis and TB meningitis, the predominant cell type is lymphoctyes.

However, I just missed a question on NBME 11 that said, in a PPD test for TB, you will get predominantly macrophages.

How is this possible? I guess I am confused b/w when macrophages come and when lymphocytes come

You have to be much more specific and deliberate with your words. "In TB meningitis the predominant cell type is..." is a nonsensical statement for communicating about a disease at this level. Are you referring to the cerebrospinal fluid analysis? Are you perhaps asking about the predominant cell type in the caseous granuloma typical of TB?

Likewise, the statement "...in a PPD test for TB, you will get predominantly macrophages" is more or less a completely meaningless statement. A PPD test doesn't "get" anything. It is a test that determines whether presensitized CD4+ T-cells are present, which will then activate macrophages to cause a type-IV hypersensitivity inflammatory response.