This protocol is designed to provide a mechanism for the Department of Transfusion Medicine, Clinical Center to collect and process blood components from paid, healthy volunteer donors for distribution to NIH intramural investigators and FDA researchers for in vitro laboratory use. Donors meeting research donor eligibility criteria will be recruited to donate blood and blood components by standard phlebotomy and apheresis techniques. The investigational nature of the studies in which their blood will be used, and the risks and discomforts of the donation process will be carefully explained to the donors, and a signed informed consent document will be obtained. Donors will be compensated according to an established schedule based on the duration and discomfort of the donation. NIH and FDA investigators requesting blood components for research use will be required to submit an electronic (Web-based) memo of request, briefly describing the nature of the research, and providing assurance that samples provided through this protocol will be used solely for in vitro and not for in vivo research. This protocol also provides a detailed schema for careful and frequent laboratory safety monitoring of repeat research apheresis donors.