Cytotoxic action of IL‐1β against pancreatic islets is mediated via nitric oxide formation and is inhibited by NG‐monomethyl‐l‐arginine

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Abstract
IL‐1β has been previously shown to act as a cytotoxic agent in islets. Here we show by electron microscopy of alginate encapsulated islets, that islet cell lysis is induced by culturing islets for 24 or 48 h in the presence of IL‐1β. The extent of lysis depends on the IL‐1β concentration and is slightly enhanced by the addition of TNF‐α. Cells can be protected from lysis by N G‐monomethyl‐l‐arginine. Lysis is paralleled by an increase in nitrite concentration in culture supernatants of whole islets but not in supernatants of isolated endocrine cells. The results indicate that IL‐1β toxicity occurs via inducing in non‐endocrine islet cells the synthesis and release of nitric oxide, which has been shown earlier to be highly toxic for islet cells.