This study will examine the feasibility of giving cell growth stimulants to granulocyte donors the same day of donation rather than the day before.

People who donate granulocytes (infection-fighting white blood cells) for transfusion to patients with severe white cell deficiencies are often given a steroid called dexamethasone and a growth factor called G-CSF the day before donation. These drugs stimulate white cell production, allowing many more cells to be collected than would otherwise be possible. A single dose of G-CSF given to healthy people increases their white cells counts by four to five times the next day.

It would be preferable, however, to give G-CSF the same day of donation, if possible. Therefore, this study will measure white cell counts in healthy people at various intervals after being injected with G-CSF alone and G-CSF with dexamethasone. The study will compare the following: granulocyte counts at seven different intervals after injection of the drug or drugs; the effects of G-CSF injected through a vein or under the skin; and the effects of giving G-CSF alone or with dexamethasone.

Each participant will undergo four procedures, each four weeks apart as follows: donate a small blood sample; receive an injection of G-CSF under the skin or into a vein; and take either two dexamethasone tablets or two placebo tablets.

Small blood samples will then be drawn 1, 2, 4, 6, 8, and 24 hours after the drugs are given. Participants will answer questions about how they feel before the drugs are given and at the various intervals after taking the drugs.