Interleukin-6 (IL-6) producing phaeochromocytoma: direct IL-6 suppression by non-steroidal anti-inflammatory drugs

A 35-year-old Japanese woman presented with a phaeochromocytoma and demonst rated marked inflammatory reactions and pyrexia as a result of excessive pr oduction of interleukin-6 (IL-6) by the tumour. Serum IL-6 level was 262 ng /l (normal; < 4.0 ng/l), Fever and inflammatory markers were largely overco me by the administration of the nonsteroidal anti-inflammatory drug, naprox en, and all symptoms disappeared soon after the tumour was excised. Immunoh istochemical study revealed positive staining using an antihuman IL-6 antib ody and Northern analysis showed increased IL-6 mRNA levels in the tumour. Cultured tumour cells showed IL-6; protein synthesis, and nonsteroidal anti -inflammatory drugs such as naproxen and indomethacin directly inhibited IL -6 release. These results indicate that the effects of naproxen in vivo wer e due, at least in part, to direct suppression of IL-6 secretion from the t umour.