IL4 and COVID-19: Notably, inflammatory cytokines, including IL-6 and TNF-α, proinflammatory/anti-inflammatory ratios (IL-6/IL-10, and IL-6/IL-4) unexpectedly kept increased within 5 days of CP treatment in almost half of patients, which was not compatible with another study on CP treatment for COVID-19.13 It is probably because that increased systemic cytokine production may lead to the pathophysiology of severe COVID-19, including ARDS and multiple organ failure,28 and it might be unable to attenuate the inflammatory damage soon after CP transfusion.