Human monocyte ATP-induced IL-1β posttranslational processing is a dynamic process dependent on in vitro growth conditions

Abstract

Despite a large production capacity, freshly isolated lipopolysaccharide (LPS)-activated human monocytes release only a small percentage of their newly synthesized interleukin (IL)-1β into the medium. Extracellular ATP, acting via surface P(2z)-type purinoreceptors, increases cytokine posttranslational processing. To explore whether this ATP response was affected by culture conditions, monocytes were maintained for different time periods in the absence and presence of various media components including fetal bovine and human sera and recombinant human cytokines. The ability of monocytes to produce radiolabeled proIL-1β in response to LPS and to posttranslationally process the procytokine after ATP stimulation was affected both by time in culture and by the presence of specific media components. These observations indicate that ATP's ability to promote human monocyte IL-1β posttranslational processing is a dynamic process that is subject to regulation by cytokines and/or growth factors. Changes in monocyte/macrophage ATP responsiveness may provide an important regulatory mechanism for the control of IL-1 biological activity in vivo.