I agree with your assessment of the "immune system" as we generally understand it; this UTR is on the mRNA and will not encounter the anti-bodies that float around between cells, in the blood, etc. looking for problems. They are separated by very well defined barriers. If that were not the case, multicellular life could not exist.
However, there are other types of "immune systems." CRISPR-Cas9 as a gene editing tool was found precisely because bacteria use it as an intracellular immune system. And CRISPR is not the only one. We have intracellular immune systems in our own cells. This mRNA could possibly cause problems with such systems. In fact the exposure of parts of the interior of the mitochondria into the cytosol is a common signal for autophagocytosis (take out the trash) or apoptosis (kill the cell).
There are several assumptions in there, but it isn't without theoretical backing (and substantial experimental backing in other organisms). This is potentially something to be concerned about.
I agree with your assessment of the "immune system" as we generally understand it; this UTR is on the mRNA and will not encounter the anti-bodies that float around between cells, in the blood, etc. looking for problems. They are separated by very well defined barriers. If that were not the case, multicellular life could not exist.
However, there are other types of "immune systems." CRISPR-Cas9 as a gene editing tool was found precisely because bacteria use it as an intracellular immune system. And CRISPR is not the only one. We have intracellular immune systems in our own cells. This mRNA could possibly cause problems with such systems. In fact the exposure of parts of the interior of the mitochondria into the cytosol is a common signal for autophagocytosis (take out the trash) or apoptosis (kill the cell).
There are several assumptions in there, but it isn't without theoretical backing (and substantial experimental backing in other organisms). This is potentially something to be concerned about.