22 Apr

Blood Typing

The procedure for blood typing was developed by Karl Landsteiner around 1900.  He determined that human blood groups can be separated into four groups on the basis of two antigens that are present on the surface of red blood cells.  These antigens are designated as A and B.  The four groups are A, B, AB, and O.  The last group, type O, which is characterized by the absence of A or B antigens, is the most common type in the U.S. (45% of the population).  Type A is next in frequency at about 39%, type B is 12% and type AB 4%.  Blood typing is performed with antisera containing high titers of anti-A and anti-B antibodies.  The test can be performed in a tube where a drop of each kind of anti-serum is added to the separate samples of saline suspensions of blood cells. pauln