In particular, in a recent study by Qin C, et al.in which among 452 patients with COVID-19, most of them had increase of several inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-1and IL-6 [
3].
Further, higher serum levels of pro-inflammatory cytokines (i.e. TNF-α, IL-1 and IL-6) were found in patients with severe COVID-19 as compared to the non-severe ones [
3]. Additionally, in severe cases, a reduction of CD4+ and CD8+ T cells and a decrease of regulatory T cells has been found, likely due to high expression of proinflammatory cytokines in COVID-19 patients [
3].
However, so far, it remains unclear why SARS-CoV-2 may lead to variable cytokine modulation and different phenotypes of patients, maybe linked to both viral characteristics and host susceptibility.