- One aims to find out the role of a gene product in macrophages by using a transgenic mouse expressing the genes under a promoter. Which of the following is the most appropriate
promoter?
(1) Actin promoter.
(2) MHC Class ll promoter.
(3) Mac-1/CD llb promoter.
(4) IL-2 promoter.The most appropriate promoter is (3) Mac‑1/CD11b promoter.
Option-wise explanation
(1) Actin promoter
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β‑actin promoters are ubiquitous and strong, driving expression in almost all cell types.
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Using this would express the transgene broadly, not just in macrophages, making it unsuitable for macrophage‑specific functional studies.
(2) MHC Class II promoter
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MHC class II is expressed on professional antigen-presenting cells: B cells, dendritic cells, macrophages, and some activated T cells.
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This promoter would drive expression in multiple immune cell types, not selectively in macrophages.
(3) Mac‑1/CD11b promoter – correct
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Mac‑1 (CD11b/CD18) is highly expressed on myeloid lineage cells, especially macrophages, monocytes, and some neutrophils.
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Transgenic constructs driven by the CD11b promoter are widely used for macrophage/myeloid‑restricted expression, making this the best choice for dissecting a gene’s role in macrophages.
(4) IL‑2 promoter
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IL‑2 is mainly produced by activated T cells.
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An IL‑2 promoter would favor expression in T lymphocytes, not macrophages, and is therefore inappropriate here.
For macrophage-focused transgenic expression, the Mac‑1/CD11b promoter (option 3) is the most specific and appropriate choice.
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