CXCL8 and infection: However, unlike results from previous studies that demonstrated the upregulated expression of the IL-8 cytokine gene, which induces chemotaxis in neutrophils and stimulate the phagocytosis, in macrophages or in a fish model after infection with Aeromonas (59–61), no upregulation of IL-8 gene in THP-1 monocytic cells could be observed in our study.