Mis C

The Immune System's Broken Off-Switch

Imagine your body's immune system is a fire department. Normally, firefighters (immune cells) respond to a fire (COVID virus), spray water (cytokines) to put it out, then pack up and go home within days. In MIS-C, the off-switch breaks: even after the fire is completely out and the building is empty, the firefighters keep spraying water everywhere. The water floods the building's walls (the endothelium, the smooth lining of blood vessels), weakening them and making them leak. Water pools in the basement (tissues swell with fluid), the main pump that feeds the building (the heart muscle) gets waterlogged and can't squeeze as hard, and pipes burst (aneurysms form in coronary arteries). Because the heart can't pump and the walls are leaking pressure, water stops flowing to the rest of the neighborhood (shock develops), and people start turning blue. The firefighters need someone to grab the nozzle and shut it off—that's what steroids and IVIG do.