The release profiles of interleukin 1 (Il-1) and tumor necrosis factor (TNF) were studied during experimental Escherichia coli4 h) the Il-1 response. During peritonitis, a delayed (30 min) but otherwise similar Il-1-response was observed. TNF levels rose rapidly (+30 min) in all animals, and remained high throughout the experimental period (6 h). The trauma did not influence the TNF response. We conclude that a synergism exists between trauma and infection with regard to the magnitude of the Il-1 respon