Clinical chemistry the denser blood cells and platelets to the bottom of the centrifuge tube, leaving the liquid serum fraction resting above the packed cells. This initial step before analysis has recently been included in instruments that operate on the "integrated system" principle. Plasma is in essence the same as serum, but is obtained by centrifuging the blood "without" clotting. Plasma is obtained by centrifugation "before" clotting occurs. The type of test required dictates what type of sample is used. A large medical laboratory will accept samples for up to about 700 different kinds of tests. Even the largest of laboratories rarely
Diego antigen system Diego antigen system The Diego antigen (or blood group) system is composed of 21 blood factors or antigens carried on the Band 3 glycoprotein, also known as Anion Exchanger 1 (AE1). The antigens are inherited through various alleles of the gene SLC4A1 (Solute carrier family 4), located on human chromosome 17. The AE1 glycoprotein is expressed only in red blood cells and, in a shortened form, in some cells in the kidney. The Diego antigen is fairly common in Indigenous peoples of the Americas (in both North and South America) and East Asians, but very rare or absent in most