3. Adequate blood counts (HIV positive volunteers: hemoglobin greater than or equal to 9.0 g/dL, HCT greater than or equal to 28%, platelets greater than or equal to 75,000; HIV negative volunteers: hemoglobin greater than or equal to 11.2 g/dL, HCT greater than or equal to 34.1%, platelets greater than or equal to 150,000).