IL1B and Stroke: Activated microglia/macrophages and infiltrating immune cells (ie, monocytes and neutrophils) are present in the infarct and in the peri-infarct area after ischemic stroke.14 Previous research showed microglial IL-1β expression 24 hours after stroke.13 NLRP3 is also described to be expressed in infiltrating cells at a similar time point.12 To further characterize the inflammatory response occurring after ischemia, we used flow cytometry of brain homogenates to measure microglia and immune cell infiltrates.