TNF and synovitis: In Cook et al. [40], increased serum levels of the lipid mediators prostaglandin E2 and thromboxane B2 were found after ischemia-induced local inflammation of the jejunum, and in a study by Campebell et al. [11], no difference in serum TNF-a concentration could be detected in LPS-induced synovitis despite significant changes in body temperature and circulating white blood cell composition in response to LPS.