IL-1β Induces Alkaline Phosphatase in Human Phagocytes

Background ne phosphatase (ALPase) is found in blood plasma or serum and leukocytes and regulates intercellular processes, maintaining phosphoryl metabolites in a steady state, as well as synthesizing and hydrolyzing phosphate esters on membranes. ALPase supervises the active transport of inorganic phosphates, fats, proteins, carbohydrates and the sodium/potassium pump mechanisms. The formed elements of blood such as polymorphonuclear (PMNs) leucocytes, macrophages (MP) and some lymphocytes are high in ALPase concentrations. s s study we have tested whether the interleukin-1 receptor antagonist (IL-lra) could influence ALPase generation in IL-1β or lipopolysaccharide (LPS)-stimulated neutrophils and MP. Human neutrophils were isolated from heparin-anticoagulated blood drawn from healthy individuals by centrifugation in a two-step gradient, Ficoll-Hypaque. ALPase activity was assessed spectrophotometrically in test tubes containing isolated neutrophils and adherence PBMCs treated with LPS, IL-1β and IL-1ra, alone or in combination. s or LPS enhanced ALPase in both PMNs and MP, whereas IL-1ra could not inhibit ALPase activity. We performed time course experiments at 0 min, 5 min, 1 h, 24 h, and 43 h (LPS 20 μg/mL, IL-1β 10 ng/mL). No significant increase in ALPase activity was seen until 1 h; however, there was a rapid rise over the next few hours. In another set of experiments using IL-1ra (500 ng/mL), there was no difference between treated cells and control cells. The combination of IL-1β plus IL-1ra did not reduce the ability of IL-1β to induce ALPase activity. sions data suggest that IL-1β stimulates ALPase through other mechanisms than the release of arachidonic acid products, which are inhibited by IL-lra.