nbme 17 qs! - alt_ast

[ArchivalUser]

A 34 yo HIV patient develops pulmonary tuberculosis. No CD4+ lymphocytes are detected in his peripheral blood. Which of the following cellular components is most likely to have a deficient function in the tuberculoids lesions in this patient lungs?

A)eosinophils
B)fibroblasts
C)langhans giant cells
D)macrophages
E)neutrophils


Hi everyone! I don't know the right answer and explanation to this question. I would really appreciate some help
Thanks in advance

[ArchivalUser]

D macrophages

[ArchivalUser]

Explain why please! Why not c)Langhans giant cells? I need the explanation !! thanks

[ArchivalUser]

killing M.tb is mainly cell mediated response-Th1 response---- activates INF-alpha ----which activates macrophages. macrophages loose their motility, accumulate at the site of injury and form epitheloid cells.---eventually transform to langherhans giant cells by fusion of these.
LH cells and fibroblasts form from the damage of macrphages. thats what is my understanding.

[ArchivalUser]

sorry typing error. LH cells form After macrphage destruction. Fibroblast get activated

[ArchivalUser]

@ketu13 thank you so much for the explanation, let me correct you in one word... You wrote langherhans giant cells.. but the proper name is Langhans giant cells. Be careful with these two words, cause they are very similar , but they are completely different things..

so we still have macrophages and langhans giant cells as two posible options...
I'm still a bit lost ...
Did you take nbme 17 online? If the right answer is macrophages I could guess... it's because macrophages can't be activated by TH1 helper cells (no CD4)... so if they can't be activated (no IFN gamma from TH1 cells) they won't be able to fuse and form langhans giant cells

Correct me if I'm wrong please

[ArchivalUser]

@alt_ast thanku so much for pointing out the difference bet these. I assumed they were same!:/ ....So,
Langhans giant cells are formed by the fusion of epithelioid cells (macrophages), and if no CD4 cells are presentin this case,then both macrophages and resulting Langhans cells should not be activated. ? I have no clue now.. may be someone can explain us both...