However, although neutrophils in healthy individuals mainly express CXCR1 and CXCR2 [31], it has been shown that infiltrated neutrophils from patients with chronic inflammatory lung diseases and rheumatoid arthritis express additional chemokine receptors on their surface, i.e., CCR1, CCR2, CCR3, CCR5, CXCR3, and CXCR4 [31]. This evidence concerns the gene CCR1 and rheumatoid arthritis.