IL6 and COVID-19: Furthermore, to assess the immunoregulatory effects of cTregs/uTregs, LAG3+cTregs/uTregs, and IL-35+IL-10+ Bregs on COVID-19 induced immune activation, we correlated the levels with serum markers of COVID-19 severity such as CRP and ferritin as well as with different circulatory proinflammatory cytokines such as IL-6, IL-17, TNFα, and IL-1β.