AIM: To study the serum concentration of IL-1β, IL-1 receptor antagonist (IL-1Ra) and IL-18 in Gαi2-deficient mice at the age of 6 (healthy), 12 (pre-colitic) and 24 wk (colitic) and in healthy control mice.METHODS: At the time of killing, serum samples were collected and IL-1β, IL-1Ra and IL-18 levels were measured using enzyme-linked immunosorbent assays.RESULTS: Serum concentration of IL-1Ra was significantly increased in pre-colitic (median: 524 ng/L;P=0.02) and colitic (450 ng/L; P=0.01), but not in healthy (196 ng/L) Gαi2-deficient mice as compared with controls (217 ng/L). Serum concentrations of IL-1β did not differ between Gαi2-deficient mice and their controls,irrespective of age, IL-18 was significantly increased in colitic, but not in pre-colitic mice compared with controls (510 ng/L vs 190 ng/L; P= 0.05).CONCLUSION: The increased serum concentrations of IL-18 and IL-1Ra in established diseases are suggested as markers of ongoing colitis. Interestingly, the significantly increased serum concentration of IL-1Ra in pre-colitic mice is found to be an early marker of disease progression.