CXCL8 and lymphopenia: Severe lymphopenia is a very early sign of the disease, preceding pulmonary problems, and tends to normalize as the patient improves.[16] On the other hand, monocytes and macrophages are increased, which may explain elevated levels of pro-inflammatory cytokines such as interleukin (IL)-6, IL-1, tumor necrosis factor (TNF)-α, and IL-8.[17]