Idiopathic pulmonary fibrosis (IPF) is a progressive, fatal disorder in which chronic accumulation of neutrophils within the alveolar structures occurs. These cells with their large stores of preformed mediators likely play a major role in subsequent lung derangement. To evaluate the adjunctive use of intermittent high dose "pulse" corticosteroid therapy as a means of inhibiting neutrophil accumulation in the IPF lung, 5 patients were treated in a single blind random fashion with "high dose" corticosteroids (2 g methylprednisolone given intravenously once a week plus 0.25 mg/kg prednisone given orally daily) and 8 patients were treated with "low dose" corticosteroids only (0.25 mg/kg prednisone given orally daily). All patients had biopsy-proved disease in midcourse, and the 2 groups were matched for clinical and physiologic criteria. To evaluate the effect of these therapies on the quantity of neutrophils in the lungs of these patients, both groups underwent bronchoalveolar lavage and 67Ga scanning at the beginning and end of the 6-month study period; both methods gave an estimate of the intensity of the neutrophil alveolitis in these patients. Low dose corticosteroids had little effect on neutrophil accumulation (% neutrophils in lavage, - 5 +/- 8% change from baseline; 67Ga uptake, + 27 +/- 14% change from baseline), whereas high dose corticosteroids significantly reduced neutrophil accumulation (% neutrophils in lavage, - 46 +/- 8% change from baseline, p less than 0.02 compared with that in the low dose group; 67 Ga uptake, - 23 +/- 11% change from baseline, p less than 0.05 compared with that in the low dose group). In addition, 2 patients in the high dose group were reevaluated 6 months after cessation of the intermittent high dose pulse corticosteroids. Both had marked increases in lavage neutrophils compared with when they were receiving the high dose therapy (10 to 22% and 18 to 52%, respectively). These findings suggest that massive doses of intermittent intravenously administered corticosteroids may help to suppress the neutrophil component of the alveolitis of IPF.