Background information: Science Kit and Boreal Laboratories
Protocol (Materials and Methods): NeoSci ABO-Rh Typing Using Neo/BLOOD
Around 1900, Karl Landsteiner discovered that there are at least four different kinds of human blood based on the presences or absence of specific agglutinogens (agglutinating antigens) on the surface of red blood cells (RBCs, also known as erythrocytes). These antigens have been designated as A and B. Antibodies against antigens A and B begin to build up in the blood plasma shortly after birth. The antibody levels peak at about eight to ten years of age, and the antibodies remain present in declining amounts throughout the rest of life. The stimulus for antibody production is not clear; however, it had been proposed that antibody production is initiated by minute amount of A- and B- antigens that may enter the body through food, bacteria, or by other means. A person normally produces antibodies against those antigens that are not present on his/her erythrocytes but does not produce against antibodies that are present on his/her erythrocytes. Thus, a person with antigen A on the surface of her/his RBCs (blood type A) will have antibodies against B antigens (anti-B antibodies); a person with antigen B on the surface of her/his RBCs (blood type B) will have antibodies against antigen A (anti-A antibodies); a person with neither A nor B antigens (blood type O) has BOTH anti-A and anti-B antibodies; a person with both A and B antigens (blood type AB) has neither anti-A nor anti-B antibodies. The individual’s blood type is based on the antigens (not the antibodies) he/she has.
The four blood groups are known as types A, B, AB, and O. Blood type O, characterized by an absence of A and B agglutinogens, is the most common in the United States (45% of the population). Type A is the next in frequency, found in 39% of the population. The incidences of types B and AB are 12% and 4%, respectively.
Table 1: The ABO System
|Blood Type |Agglutinogens |Agglutinins |Can GIVE Blood to |Can RECEIVE | | |(Antigens on |(Antibodies in the |Groups: |Blood from | | |Erythrocytes) |Blood) | |Groups: | |A |A |Anti-B |A, AB |O, A | |B |B |Anti-A |B, AB |O, B | |AB |A and B |Neither anti-A |AB |O, A, B, AB | | | |Nor anti-B | | | |O |Neither A nor B |Both anti-A and |O, A, B, AB |O | | | |Anti-B | | |
Process of Agglutination
Blood typing is performed with antisera containing high levels of anti-A and anti-B agglutinins. The simple test is performed as follows:
Several drops of each kind of antiserum are added to separate samples of blood. If agglutination (clumping of erythrocytes) occurs only in the suspension to which only anti-A serum was added, the blood type is A. If agglutination occurs only in the anti-B mixture, the blood type is B. Agglutination in both samples indicates that the blood type is AB. The absence of agglutination indicates that the blood type is O.
Table 2: Agglutination...