CCL3 and COVID-19: Additionally, characterization of immune cells in the airways of COVID-19 patients showed that patients with severe or critical infection had greater abundance of monocyte-derived macrophages expressing high levels of inflammatory cytokines such as interleukin (IL)-8, IL-6, and IL-1b and chemokines, CCL2, CCL3, CCL4, and CCL7, which promoted additional recruitment of monocytes and neutrophils (Liao et al., 2020).