Inactivation of interleukin‐8 by aminopeptidase N (CD13)

Kanayama, Naohiro; Kajiwara, Yayoi; Goto, Junko; Maradny, Emad EL; Maehara, Kayoko; Andou, Katuaki; Terao, Toshihiko

Aminopeptidase (APN) was found to degrade interleukin‐8 (IL‐8) and inactivate its chemotactic activity. The chemotactic activity of IL‐8 was decreased by APN or neutrophil plasma membranes dose‐ and time‐dependently. The chemotactic activity was not inactivated in the presence of bestatin or WM15 monoclonal antibody. The expression of IL‐8 was measured by flow cytometry. On lipopolysaccharide (LPS) stimulation, IL‐8 expression increased for 60 min and then decreased markedly. In contrast, on treatment with LPS and bestatin, the expression of IL‐8 increased continuously for at least 120 min. These results suggest that the expression and release of IL‐8 from phagocytic cells are regulated by the proteolytic effect of APN on IL‐8. J. Leukoc. Biol. 57: 129–134; 1995.