NBME 11 spoiler alert - help!

[ohyeahbaby]

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A question from NBME 11:

A 28-year-old woman undergoes PPD skin testing to determine previous infection with Mycobacterium tuberculosis. Results show a 25-mm, firm area of induration at 48 hours. Analysis of this patient's lesion is most likely to show a predominance of which of the following cell types?

A) B lymphocytes
B) Cytotoxic T lymphocytes
C) Eosinophils
D) Macrophages
E) Mast cells
F) Neutrophils

The answer was D, which is Macrophages


A question I just did in uWorld:

A 34-year-old electric company worker presents to the urgent care clinic with a pruritic skin rash on his right arm. He relates the rash to recent plant exposure while doing a repair job for his company in a wooded area. Physical examination reveals a linear eruption with vesiculation. Which of the following cells would be found earliest in this patient's skin lesion?

A. Mast cells
B. Eosinophils
C. Neutrophils
D. Macrophages
E. T lymphocytes
F. Plasma cells

The answer was E, which is T-lymphocytes.

I'm extremely confused. I thought both questions were referring to a type 4 hypersensitivity scenario. If anyone can shed some light on this for me, I would appreciate it.

 

[just one]

Cytotoxic t cells are cd8 cells where type IV is cd4 cells if memory serves correctly. Machrophage presents to cd4 cell In type IV

 

[biobukowski]

I agree with the previous one. Like most USMLE Step 1 questions, there is a basic principle they're testing you on. Type 4 hypersensitivity reactions are T-cell mediated, with macrophage recruitment. Cytotoxic T-cells are not mediators (not Helpers), they're "Effectors" ie, "killers" (cyto-toxic, meaning kills cells).
In a simplified view, T-cells would arrive first, sample the antigen, then activate the macrophages by releasing specific cytokines. The first question asks, "which cell type is PREDOMINANT" and the second question asks, "which cell type ARRIVES FIRST". Though the UWorld question is sort of unfair, and to be honest, if the NBME question were to say "T-cell" or "Helper T-cell" or "CD4+ T-cell" I would pick that answer over macrophages.

 

[loveoforganic]

I thought the antigen sampling was by macrophages/dendritic cells, which presented to Th cells, no?