TUMOR-NECROSIS-FACTOR ACCOUNTS FOR THE NEUTROPHIL EMIGRATION ACTIVITYRELEASED BY CULTURED MALIGNANT FIBROUS HISTIOCYTOMA CELLS

Cultured malignant fibrous histiocytoma (MFH) cells obtained from a sp ontaneous and transplantable rat tumor were studied for their ability to release tumor necrosis factor (TNF) and a factor which induces neut rophil migration in vivo. MFH cells obtained from 7-day cultures spont aneously released both activities into the supernatant (TNF: 36 +/- 9 IU TNF/ml supernatant, N = 3; neutrophil chemoattractant factor: contr ol, Medium ip: 6 +/- 1 x 10(6); MFH supernatant: 18 +/- 1 x 10(6) neut rophils/cavity, N = 5). These releases were enhanced by treating MFH c ells with LPS (TNF: 61%; neutrophil chemoattractant factor: 46%) and w ere abolished by the glucocorticoid dexamethasone (TNF: 68%; neutrophi l chemoattractant factor: 100%). Anti-TNF antiserum abolished the neut rophil chemoattractant activity of the supernatants (95%). The release of TNF or neutrophil chemoattractant activity was reduced in cells ob tained 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 histioc yte-like cells as determined by nonspecific esterase methods. The numb er of these cells decreased as the cultures aged (7-day culture, 71%; 14-day culture, 5%; 21-day culture, 0%). In conclusion, our results sh ow;t strong association between the intensity of the neutrophil chemoa ttractant activity and TNF concentration in the supernatants. This ass ociation, together with the observed inhibition of the neutrophil chem oattractant activity of the supernatants by TNF neutralizing antibodie s, supports the suggestion that TNF may be responsible for the neutrop hil chemoattractant activity present in the supernatants. The release of TNF by MFH tumor cells may account for the neutrophil infiltration observed with this type of tumor in vivo.