A Randomized Phase II Study of Two Doses of Interferon Alfa-2a (IFN Alfa-2a) in Combination With Zidovudine (AZT) and Dideoxycytidine (ddC) Versus AZT and ddC Only in Patients With HIV Infection and Less Than 400 CD4 Cells/mm3

Inclusion Criteria Concurrent Medication: Allowed: * Isoniazid for \< grade 2 peripheral neuropathy (if patient is also taking 50 mg/day pyridoxine). * Phenytoin for \< grade 2 peripheral neuropathy. * A 21-day course of adjuvant systemic corticosteroid therapy for moderate to severe Pneumocystis carinii pneumonia (PCP). * Chemoprophylaxis for PCP, candidiasis, herpes simplex infection (up to 1 g acyclovir daily), and Mycobacterium tuberculosis. Patients must have: * HIV infection. * CD4 count \< 400 cells/mm3 within 30 days prior to study entry. NOTE: * Minimal Kaposi's sarcoma is allowed. Exclusion Criteria Co-existing Condition: Patients with the following symptoms and conditions are excluded: * Active opportunistic infection requiring acute therapy. * Need for maintenance therapy for cytomegalovirus infection, toxoplasmic encephalitis, or mycobacterial infection. * Malignancy (other than minimal Kaposi's sarcoma) requiring therapy. * Grade 2 or worse peripheral neuropathy. Concurrent Medication: Excluded: * Other antiretroviral drugs, biologic response modifiers, cytotoxic chemotherapy, or investigational drugs (unless approved by the protocol chairs). * Recombinant erythropoietin, G-CSF, or GM-CSF. * Drugs that cause peripheral neuropathy, e.g., gold, hydralazine, nitrofurantoin, vincristine, cisplatin, disulfiram, and diethyldithiocarbamate (unless approved by the protocol chairs). Concurrent Treatment: Excluded: * Radiation therapy (unless approved by the protocol chairs). Patients with the following prior conditions are excluded: * History of intolerance to AZT at 600 mg/day or less. * Unexplained temperature of 38.5 degrees C persisting for 14 days or longer. * Unexplained, chronic diarrhea defined as 3 or more stools per day persisting for 14 days or longer. Prior Medication: Excluded: * Acute therapy for opportunistic infection within 14 days prior to study entry. * Prior ddC, ddI, or IFN alfa-2a. Active substance abuse.