Acute application of interleukin-1β induces Ca2+ responses in human microglia

The effects of the pro-inflammatory cytokine interleukin-l-beta (IL-1 beta) on levels of intracellular calcium [Ca2+](i) in cultured human microglia have been studied using the fluorescent Ca2+ indicator fura-2. IL-1 beta (2 ng/ml) caused a slow, progressive increase in [Ca2+](i) in standard Ca2+-containing physiological solution (PSS). A similar effect was observed in separate studies using Ca2+-free PSS, however, the mean rate of increase was significantly lower than that measured with PSS. Similar results were obtained in a separate protocol, where cells were exposed to both IL-1 beta in Ca2+-free PSS and PSS, The slope of the IL-1 beta induced increase of [Ca2+](i) in Ca2+-free PSS was not altered when adenosine triphosphate was added prior to application of the cytokine. These results suggest that 1L-1 beta-induced responses in human microglia involve both a Ca2+ entry pathway and a mechanism of intracellular increase other than from IP3-sensitive stores. (C) 2000 Elsevier Science ireland Ltd. All rights reserved.