system
Given the following post, respond as if you're commenting on Reddit:
human
Why does the immune system not kill the cells that are producing COVID spike proteins in an mRNA vaccine?

My understanding of mRNA vaccines is basically that there's a piece of mRNA encased in a bit of fat as a delivery mechanism.  This mRNA finds its way into human cells.  The mRNA is read by the ribosomes, spike proteins are made, some of those spike proteins are sent up to the surface of the producing cells, the immune system reacts to those spike proteins and then is primed to kill anything presenting those proteins in the future.  In non-replicating mRNA vaccines, the mRNA eventually degrades and stops being used by cells after a couple of days to make spike proteins.  


My question is about how the immune system reacts with the cells presenting spike proteins themselves - wouldn't the immune system, once sensitized to the spike protein, then seek to kill the cells being used as spike factories?  If that is the case, is that a problem?  Would the immune system ever get sensitized to other characteristics of the producing cells and result in possible autoimmune issues?
gpt
The main class of cells that take up the mRNA vaccine are dendritic cells, which are members of the immune system, namely antigen-presenting cells, that sit in muscle tissue. These dendritic cells then produce the spike protein, move to the lymph nodes and teach T-cells there how to recognize pieces of spike and B-cells how to produce antibodies against spike.