Patients will be in isolation in the hospital from the start of therapy until sputum samples show no evidence of tuberculosis for 3 consecutive weeks. Following that, they will repeat the tests done on admission (except CT) during follow-up visits (1- to 2-day hospitalizations) at 3, 6, 9, 12, 15, 18 and 24 months after the start of therapy. Patients taking interferon gamma will have blood drawn more frequently (monthly) for the first 6 months, and patients with lung infection will have sputum samples collected more frequently-weekly for the first 3 months or until three consecutive negative samples are obtained and then monthly throughout the course of therapy. Patients with lung infection will also have repeat CT scans at 6 and 12 months while on interferon gamma. In one or two patients on the drug, blood will be drawn frequently following one injection of gamma interferon (just before the injection and again at 0.25, 0.5, 1, 6, 12, 18, 24 and 48 hours after it) to see if a difference in blood levels of the drug can be detected.