Today in class, our teacher was discussing about the pathogenecity of the HIV virus.

He said that the binding between HIV virus and macrophages is done by the interaction between the GP120 of the virus and CD4 receptors,chemokine receptors(CCR-5 and CXCR-4) and fusin receptor present on Macrophages.

My doubt is I think CD4 receptors are present on T-helper cells only. Are they present on Macrophages too? Do i have a wrong notion about CD4 receptors? If not, then are there some other receptors responsible for the transfer of viral particles inside monocytes and dendritic cells?

Any extra information is appreciated.

  • $\begingroup$ Macrophages and monocytic cells can express CD4, CD8 or even co-express them. $\endgroup$ – CKM Nov 14 '17 at 17:15
  • $\begingroup$ @CMosychuk - what's the function of these receptors on monocytes? As in I know their function in T helper and T cytotoxic, but What are they doing on monocytes? $\endgroup$ – anamika Singh Nov 15 '17 at 9:12

Macrophages and monocytic cells can express CD4, CD8 or even co-express them. The CD4 and CD8 molecules interact with MHC complexes on neighboring cells, and as you can imagine elicit varying effect in a cell type-dependent manner.

Plainly enough, Zhen et al. demonstrated that monocytic CD4 ligation to MHC-II molecules on other cells, such as activated endothelium, induced an expression pattern conducive to macrophage differentiation (1). Gibbings et al. also demonstrated that CD8 associates with FcyR on the monocyte's surface similar to CD8/TCR associations, and stimulates the secretion of cytokines (2).

I'll try to find a model source, but CD8a on dendritic cells can associate with MHC-II molecules on T cells like HLA-DR and aid in cross-priming the T cells.

Now what CD4 does on functional, differentiated macrophages is less clear to me, and I need to review the literature on that a bit more. It could just be expression imprinted because they're monocyte-derived cells, or it could also elicit an effect like CD8/FcryR above. I do not know.

There are more cases, so these serve as selected examples.

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  • $\begingroup$ Thank you! It was helpful. But if you get any extra information related to this, please post it up too! =) $\endgroup$ – anamika Singh Nov 16 '17 at 16:11

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