Serum monocyte chemotactic protein-1, macrophage migration inhibitory factor, macrophage inflammatory protein-1, and IL-8 levels, which are involved in regulating monocyte/macrophage function, were higher in RP patients than in HCs (24, 25), suggesting the critical roles of monocytes, neutrophils, and lymphocytes in the pathogenesis of RP. Here, CCL2 is linked to retinitis pigmentosa 1.