Examination of systemic tumor necrosis factor activity under physiological and pathophysiological conditions

Tumor necrosis factor (TNF) activity in the circulation of several animal species was determined by a bioassay, using the murine cell line L929. In healthy adult cattle, horses, pigs and dogs, species specific differences of systemic TNF activity were visible. In cattle, TNF activity in the circulation increased during growing up from calf to adult animal. In cattle suffering from various diseases, unchanged, elevated, but also reduced systemic TNF activity have proved to posess clinical relevance. Low systemic TNF activity frequently occurs during lethal inflammatory diseases and may be an indicator of generalized monozyte paralysis.