TNF and COVID-19: To explain the coexistence of lymphopenia and hypercytokinemia in COVID-19, Diao et al. suggested that the source of IL-6, IL-10, and TNF-α was innate immune cells such as macrophages and monocytes rather than T cells and that these cytokines promote apoptosis of T cells and lead to lymphocytopenia in SARS-CoV-2 patients [34].