Interleukin 1 receptor antagonist (IL-1Ra) deficiency does not predispose to spontaneous uveitis. The onset and severity of uveitis was monitored over time in wild-type (WT) and IL-1Ra knockout (KO) mice with and without an intraperitoneal injection of 25 μg LPS at 7 weeks as in figure 1. The leucocyte trafficking response in the iris was assessed by intravital microscopy, and the numbers of rolling (A), adherent (B) and infiltrating (C) cells were quantified (n=14–17 mice/treatment/genotype/time). Results shown are combined from two independent experiments. (D) shows representative histological images of the naïve eyes of IL-1Ra KO mice at 20 weeks of age, and (E) displays the corresponding numbers of cells present in the aqueous humour (A) and vitreous body (P). CB, ciliary body; C, cornea; I, iris; ONL, outer nuclear layer; INL, inner nuclear layer; GCL, ganglion cell layer. Original magnifi cation: ×200.