IL1B and arthritic joint disease: To understand how gene expression varies with inflammation, we sorted neutrophils from mice undergoing three established models of sterile inflammation: K/BxN serum-induced arthritis (blood and joint lavage 7 days after i.p. administration of arthritogenic serum); IL-1β pneumonitis (lung lavage 3 h after i.n. instillation of 25 ng IL-1β); and IL-1β peritonitis (peritoneal lavage 3 h after i.p. 25 ng IL-1β) (Fig. 7a)6.