Although the exact nature of the immunostimulatory signals activating macrophages in cystinosis is still unknown, it was hypothesised by Elmonem et al. that cells damaged by the crystals release damage-associated molecular patterns (DAMPs) that, in turn, initiate inflammatory responses by triggering various cells, including tissue-resident macrophages, and result in the release of pro-inflammatory cytokines and chemokines—such as IL-1β, IL-6, tumour necrosis factor-α (TNF-α), and monocyte chemoattractant protein-1 (MCP-1). This evidence concerns the gene CCL2 and cystinosis.