Draw blood plasma. Donors are paid for this, based upon their weight.
Your blood is made up of a liquid portion and a cellular portion. The cellular portion contains white blood cells that fight infection, red blood cells that carry oxygen, and platelets that aid clotting. Plasma is the liquid portion of your blood. It has a number of vital functions in bleeding and infection control. It contains proteins and antibodies, which are produced by the immune system to fight diseases.
Plasmapheresis is a blood donation process in which you only donate the liquid portion of your blood, the plasma. The cellular portion of your blood is separated from the plasma by an automated instrument that is approved by the Food and Drug Administration (FDA). As part of this same automated process, the cellular portion is returned to you and the liquid plasma portion is retained in a special collection container.