Cultured malignant fibrous histiocytoma (MFH) cells obtained from a spontaneous and transplantable rat tumor were studied for their ability to release tumor necrosis factor (TNF) and a factor which induces neutrophil migration in vivo. MFH cells obtained from 7-day cultures spontaneously released both activities into the supernatant (TNF: 36 +/- 9 IU TNF/ml supernatant, N = 3; neutrophil chemoattractant factor: control, Medium ip: 6 +/- 1 x 10(6); MFH supernatant: 18 +/- 1 x 10(6) neutrophils/cavity, N = 5). These releases were enhanced by treating MFH cells with LPS (TNF: 61%; neutrophil chemoattractant factor: 46%) and were abolished by the glucocorticoid dexamethasone (TNF: 68%; neutrophil chemoattractant factor: 100%). Anti-TNF antiserum abolished the neutrophil chemoattractant activity of the supernatants (95%). The release of TNF or neutrophil chemoattractant activity was reduced in cells obtained from older cultures (14 and 21 days) (TNF: 7-day culture, 36 +/- 9; 14-day culture, 19 +/- 2; 21-day culture, 19 +/- 1 IU of TNF/ml; neutrophil chemoattractant activity: 7-day culture, 18 +/- 1.6; 14-day culture, 13 +/- 3; 28-day culture, 8 +/- 1 x 10(6) neutrophils/cavity). The predominant cells present in 7-day cultures of MFH were histiocyte-like cells as determined by nonspecific esterase methods. The number of these cells decreased as the cultures aged (7-day culture, 71%; 14-day culture, 5%; 21-day culture, 0%). In conclusion, our results show a strong association between the intensity of the neutrophil chemoattractant activity and TNF concentration in the supernatants.(ABSTRACT TRUNCATED AT 250 WORDS)