Patients who have had oral candida infection documented by morphology, or by response to antifungal therapy, or oral hairy leukoplakia, or herpes zoster infection within 2 years of anticipated study entry at any time will be excluded. Patients with a prior history of a malignancy other than cutaneous basal cell carcinomas or cervical carcinoma in situ and patients with a significant chronic underlying medical illness that would impair continuous participation in the study will be excluded.