Interleukin 8 (IL-8) and the release of leukocytes from the bone marrow

Interleukin 8 (IL-8) is produced by various cells upon stimulation and infl uences a variety of functions of leukocytes in particular neutrophils. Syst emic administration of IL-8 induces a rapid neutropenia associated by seque stration of neutrophils in the lung that is followed by a neutrophilia char acterized by the rapid release of neutrophils from the bone marrow. These c ells are released predominantly from the bone marrow venous sinusoids. In a ddition, several studies have shown the potential role of IL-8 in hematopoi esis and trafficking of hematopoietic stem cells. Systemic administration o f IL-X induces a rapid mobilization of progenitors from the bone marrow wit h long-term myelo-lymphoid repopulation capacity. It has been employed clin ically to mobilize hematopoietic progenitor cells into the peripheral blood and used for autologous or allogeneic bone marrow transplantation. The mec hanism for these effects of IL-8 is largely speculative. This report summar izes current ideas on the possible mechanisms how IL-8 influences cell traf ficking in and from the bone marrow.