CXCR1 and COVID-19: Furthermore, upon bacterial challenge, a similar pattern of cell surface receptor phenotype with reduced expression of CXCR1, CXCR2, CXCR3, CCR1, CCR5 and the maturation marker CD15, with increased expression of CXCR4 and CD66b was found in neutrophils from acute-phase COVID-19 patients (Fig 5A–5F and S7C–S7F Fig).