IL13 and systemic sclerosis: Our studies demonstrate that pooled supernatants from adult SSc PBMC co-cultured with CI contain significant levels of many profibrotic cytokines compared to controls (PDGF-AA, PDGF-BB, PDGF-AB, EGF, IGFBP-2, HGF, MCSFR, and IL-13) [6, 26–29].