Do Macrophages Have a Nucleus Based on MHC Molecule Presence?

[sameeralord]

MHC1 molecules are in all nucleated cells. MHC2 is in macrophages, does this mean they have no nucleus or they have one. Thanks

 

[bobze]

yes they do

 

[bobze]

In fact Big Macs can be multinucleated in some circumstances.

 

[Ryan_m_b]

As part of the immune response macrophages can form multinucleated giant cells.

 

[sameeralord]

Thanks for the replies So that means if a macrophage becomes infected with a virus, it would show both MHC1 and MHC2 markers.

 

[Ryan_m_b]

Thanks for the replies So that means if a macrophage becomes infected with a virus, it would show both MHC1 and MHC2 markers.

If I remember correctly MHCII is expressed when the cell in question presents the antigen of phagocytosed bacteria and other pathogens.

 

[med17k]

Phagocytes are of course nucleated . The only unnucleated cells in Humans are Platelets and RBCs But what does this have to do with MHC 1 or MHC2?

 

[bobze]

Thanks for the replies So that means if a macrophage becomes infected with a virus, it would show both MHC1 and MHC2 markers.

Almost all cells express MHCI. Except for those pointed out. There are other cells which also express low levels of MHCI like thyrocytes.

Remember that MHCI is important for expressing "self" or internal antigen and processing for that must go through the ER.

MCHII is expressed on professional antigen presenting cells like macrophages, dendritic cells, B-cells etc. This is for expressing external antigen and is processed through endosomes.

Also remember that MHCII is presented to CD4 T-cells and depending on their expression of cytokines elicits either a Th1 or Th2 type response (1 for cell mediated, 2 for antibody mediated). MHCII activation also requires CD40 as a coactivator to get that CD4 response.

 

[bobze]

The only unnucleated cells in Humans are Platelets and RBCs But what does this have to do with MHC 1 or MHC2?

Because as a rule of thumb, people remember that MHC1 expression is to monitor internal antigen. Since unnucleated cells lack the cellular machinery for viral replication they aren't good targets for viruses. This means they don't really "need" MHCI to be monitored for cell-mediated immunity.

However, if you're something like Plasmodium this works out to your advantage.