IL6 and COVID-19: IL-6 signaling blockade by tocilizumab, a monoclonal Ab (mAb) against IL-6 receptor (CD126), is an approved treatment for certain autoimmune disorders such as RA, and is also being tested for the treatment of COVID-19, with current data showing reduction in the rate of mechanical ventilation or death in severely ill patients, when given at the right time point (24–28).