High-glucose–induced expression of IL-1β by human β-cells. Cultured human islets were exposed for 4 days to media containing
5.5 (not shown) or 33.3 mmol/l glucose and gold-immunolabeled for insulin (A) or IL-1β (B–D) as previously described (19,20). Light microscopy of consecutive semi-thin sections of a human islet showing the high degree of coexistence of insulin (A) and IL-1β (B) is shown, as is electron microscopy of an ultra-thin section of a β-cell (C and D). At higher magnification, immunogold-labeled IL-1β (dense spherical particles) can be localized to the secretory granules
as characterized by a dense core (D). Samples were prepared and evaluated by two investigators (E.E. and M.R.) blinded to the treatment conditions. IL-1β was
detected only in β-cells exposed to high glucose.