Serum (blood) small molecules to cells. Like many other mass nouns, the word "serum" can be pluralized when used in certain senses. To speak of multiple serum specimens from multiple people (each with a unique population of antibodies), physicians sometimes speak of sera (the Latin plural, as opposed to *"serums"). Serum (blood) In blood, the serum () is the component that is neither a blood cell (serum does not contain white blood cells- leukocytes, or red blood cells- erythrocytes), nor a clotting factor; it is the blood plasma not including the fibrinogens. Serum includes all proteins not used in blood clotting and
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