Investigating IL-1β secretion using real-time single-cell imaging

The pro-inflammatory cytokine interleukin (IL)-1β is an important mediator of the inflammatory response. In order to perform its role in the inflammatory cascade, IL-1β must be secreted from the cell, yet it lacks a signal peptide that is required for conventional secretion, and the exact mechanism of release remains undefined. Conventional biochemical methods have limited the investigation into the processes involved in IL-1β secretion to population dynamics, yet heterogeneity between cells has been observed at a single-cell level. Here, greater sensitivity is achieved with the use of a newly developed vector that codes for a fluorescently labelled version of IL-1β. Combining this with real-time single-cell confocal microscopy using the methods described here, we have developed an effective protocol for investigating the mechanisms of IL-1β secretion and the testing of the hypothesis that IL-1β secretion requires membrane permeabilisation.