This model of arthritis is dependent upon IgG, FcγRs, complement, leukotriene B4 (LTB4), and IL-1β and is not dependent upon the adaptive immune system, yet requires a variety of innate immune cells — including mast cells, macrophages, and neutrophils — allowing the study of the innate immune system in arthritis (12). This evidence concerns the gene IL1B and Arthritis.