Strikingly, loss of IL-15 or IL-15Rα during CCl4- induced liver fibrosis resulted in significant reduction in the number of CCR2+Ly6CHi proinflammatory macrophages compared to wildtype mice, whereas the number of CX3CR1+Ly6CLo anti-inflammatory macrophages were significantly reduced only in Il15ra–/– mice compared to wildtype controls. The gene discussed is IL15RA; the disease is Hepatic fibrosis.