Wiley Medical mTOR Inhibitors Virology Review, page-6

WARNING- DON'T RELY ON THIS AS I'M IGNORANT ABOUT THESE MATTERS AND I'M JUST TRYING TO MAKE SENSE AS BEST AS I CAN:

The gist of it, as far as I can make out, is that there are different types of cytocines, which are released by cells as a communication method between cells to incite an orchestrated response as needed, ie for instance as part of an immune response in some cases. Unfortunatley a viral infection like sars/covid 19 can cause such a response in some people to go beserk, and cause a "cytocine storm" , which leads to dangerous inflammations, and conditions like pseumonia in some people suffering from a viral attack, By giving mpl, presumably at an early enough stage in the infection, such a cytokine over reaction can be minimised or prevented, or at least that's what I gather from the above study.