Pilot Study: Effects of G-CSF on T Cell Function

This study will evaluate changes in T cells-infection-fighting white blood cells of the immune system-in people given a drug called G-CSF before donating stem cells (immature bone marrow cells) for transplantation. Originally, bone marrow cells were obtained using a needle inserted into the hipbone of the donor. However, when it was discovered that immature bone marrow cells also circulate in the blood, scientists began to develop techniques to collect quantities of these cells from the blood instead of the bone. G-CSF is a blood cell growth factor that pushes stem cells from the bone marrow into the bloodstream. Stem cell donors are given this drug 5 to 6 days before donation to make more cells available in the circulating blood for collection.

Stem cell transplantation requires careful regulation of immune cell function to allow the donated stem cells to grow in the transplant recipient, to prevent the transplanted cells from damaging the recipient, and to allow the recipient's new immune system to develop normally so it can fight infections. Studies comparing the outcome of patients transplanted with bone marrow cells with those transplanted with stem cells suggest that the G-CSF given to stem cell donors affects the function of T cells in transplant recipients. This study will collect white cells containing T cells before and after G-CSF administration to determine the effects of the drug on both T cells and stem cells.

Healthy normal volunteers 18 years of age and older who meet the health criteria for donating blood may participate in this study. Pregnant and breastfeeding women are not eligible.

Participants will undergo the following procedures:

• Blood sample collection (15 milliliters, or 3 teaspoons) to measure blood cell counts
• Electrocardiogram to assess heart function
• Apheresis to donate white blood cells. Participants will undergo two apheresis procedures-once before receiving G-CSF and a second time immediately after finishing the 5-day course of the drug. For this procedure, whole blood is removed using a needle placed in an arm vein. The blood is circulated through a cell separator machine, where the white cells are removed and collected in a plastic bag. The rest of the blood, including the red cells, platelets, and plasma, are returned to the donor through a needle in the other arm. The procedure takes 2 to 3 hours, during which time the donor lies quietly.