Interferon a-2b had been used in eight patients (62%), while interferon a-2a and lymphoblastoid interferon (6 MU q.d. 9 10 days, then 6 MU t.i.w.) was used in one single case. Interferon type was not specified in three cases. Dosages regimes varied with type of interferon and are presented in Table 2 . Onset of symptoms of interstitial pneumonitis ranged from 20 days to 23 weeks of therapy. Symptoms included cough, dyspnea, and fever.