This year marks the 15th Anniversary of WARD’S Simulated Blood, a completely safe product that looks and acts like real blood, that can be safely used by students to look at all four types of human blood. To help celebrate this amazing product, we would like to share so of the history of the study of blood and blood typing.
Around 1900, Karl Landsteiner discovered that there are at least four different kinds of human blood, determined by the presence or absence of specific agglutinogens (antigens) on the surface of red blood cells (erythrocytes). These antigens have been designated as A and B. Antibodies against antigens A or B begin to build up in the blood plasma shortly after birth, the levels peak at about eight to ten years of age, and the antibodies remain, in declining amounts, throughout the rest of a person’s of life.
The stimulus for antibody production is not clear; however, it has been proposed that antibody production is initiated by minute amounts of A and B antigens that may enter the body through food, bacteria, or other means. Humans normally produce antibodies against those antigens that are not on their erythrocytes: A person with A antigens has anti-B antibodies; a person with B antigens has anti-A antibodies; a person with neither A nor B antigens has both anti-A and anti-B antibodies; and a person with both A and B antigens has neither anti-A nor anti-B antibodies (Figure 1). Blood type is based on the antigens, not the antibodies, a person possesses.
The four blood groups are types A, B, AB, and O. Blood type O, characterized by the absence of A and B agglutinogens, is the most common in the United States and is found in 45% of the population. Type A is next in frequency, and is found in 39% of the population. The frequencies at which types B and AB occur are 12% and 4% respectively.
Process of Agglutination
There is a simple test performed with antisera containing high levels of anti-A and anti-B agglutinins to determine blood type. Several drops of each kind of antiserum are added to separate samples of blood. If agglutination (clumping) occurs only in the suspension to which the 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 in any sample indicates that the blood type is O.
Importance of Blood Typing
As noted in the table above, people can receive transfusions of only certain blood types, depending on the type of blood they have. If incompatible blood types are mixed, erythrocyte destruction, agglutination and other problems can occur. For instance, if a person with type B blood is transfused with blood type A, the recipient’s anti-A antibodies will attack the incoming type A erythrocytes. The type A erythrocytes will be agglutinated, and hemoglobin will be released into the plasma. In addition, incoming anti-B antibodies of the type A blood may also attack the type B erythrocytes of the recipient, with similar results. This problem may not be serious, unless a large amount of blood is transfused.
The ABO blood groups and other inherited antigen characteristics of red blood cells are often used in medico-legal situations involving identification of disputed paternity. A comparison of the blood groups of mother, child, and alleged father may exclude the man as a possible parent. Blood typing cannot prove that an individual is the father of a child; it merely indicates whether or not he possibly could be. For example, a child with a blood type of AB, whose mother is type A, could not have a man whose blood type is O as a father.
DID YOU KNOW? Donor blood contains only packed red blood cells. There is no plasma in donor blood, thus there are no antibodies present.
DID YOU KNOW? Camels and their relatives are the only mammals having oval red blood cells.
The Genetics of Blood Types
The human blood types (A, B, AB, and O) are inherited by multiple alleles, which occurs when three or more genes occupy a single locus on a chromosome. Gene IA codes for the synthesis of antigen (agglutinogen) A, gene IB codes for the production of antigen B on the red blood cells, and gene i does not produce any antigens. The phenotypes listed in the table below are produced by the combinations of the three different alleles: IA, IB, and i. When genes IB and IA are present in an individual, both are fully expressed. Both IA and IB are dominant over i so the genotype of an individual with blood type O must be ii (Figure 3).
| Phenotype |
Possible Genotypes |
| A |
IAIA IAi |
| B |
IBIB IBi |
| AB |
IAIB |
| O |
ii |
Use IA for antigen A, IB for antigen B, and i for no antigens present.
Genes IA and IB are dominant over i.
AB blood type results when both genes IA and IB are present.
Rh System
In the period between 1900 and 1940, a great deal of research was done to discover the presence of other antigens in human red blood cells. In 1940, Landsteiner and Wiener reported that rabbit sera containing antibodies for the red blood cells of the Rhesus monkey would agglutinate the red blood cells of 5% of Caucasians. These antigens, six in all, were designated as the Rh (Rhesus) factor, and they were given the letters C, c, D, d, E, and e by Fischer and Race. Of these six antigens, the D factor is found in 85% of Caucasians, 94% of African Americans, and 99% of Asians. An individual who possesses these antigens is designated Rh+; an individual who lacks them is designated Rh-.
The genetics of the Rh blood group system is complicated by the fact that more than one antigen can be identified by the presence of a given Rh gene. Initially, the Rh phenotype was thought to be determined by a single pair of alleles. However, there are at least eight alleles for the Rh factor. To simplify matters, consider one allele: Rh+ is dominant over Rh-; therefore, a person with an Rh+/Rh- or Rh+/Rh+ genotype has Rh+ blood.
The anti-Rh antibodies of the system are not normally present in the plasma, but anti-Rh antibodies can be produced upon exposure and sensitization to Rh antigens. Sensitization can occur when Rh+ blood is transfused into an Rh- recipient, or when an Rh- mother carries a fetus who is Rh+. In the latter case, some of the fetal Rh antigens may enter the mother’s circulation and sensitize her so that she begins to produce anti-Rh antibodies against the fetal antigens. In most cases, sensitization to the Rh antigens takes place toward the end of pregnancy, but because it takes some time to build up the anti-Rh antibodies, the first Rh+ child carried by a previously unsensitized mother is usually unaffected. However, if an Rh- mother, or a mother previously sensitized by a blood transfusion or a previous Rh+ pregnancy, carries an Rh+ fetus, maternal anti-Rh antibodies may enter the fetus’ circulation, causing the agglutination and hemolysis of fetal erythrocytes and resulting in a condition known as erythroblastosis fetalis (hemolytic disease of the newborn). To treat an infant in a severe case, the infant’s Rh+ blood is removed and replaced with Rh- blood from an unsensitized donor to reduce the level of anti-Rh antibodies.
Blood Components
The formed elements in blood include erythrocytes, or red blood cells (RBCs); various types of leukocytes, or white blood cells (WBCs); and platelets.
Erythrocytes are circular, biconcave disks of 5 to 8 micrometers. Their chief function is to transport oxygen (O2) and carbon dioxide (CO2). The transport of O2 and CO2 depends largely on the hemoglobin present in the erythrocytes. The biconcave shape is also related to the erythrocytes function of transporting gases, in that it provides an increased surface area through which gases can diffuse.
The number of circulating RBCs is closely related to the blood’s oxy-gen-carrying capacity. Any changes in the RBC count may be significant. RBC counts are routinely made to diagnose and evaluate the course of various diseases.
Leukocytes range in size from approximately 9 to 25 micrometers and function primarily to control various disease conditions. Leukocytes can move against the current of the bloodstream through amoeboid movement, and pass through the blood vessel walls to enter the tissues. The total WBC count normally varies from 5,000 to 10,000/mm3. Certain infectious diseases are accompanied by an increase in WBCs. If the number exceeds 10,000/mm3, the person has an acute infection. If it drops below 5,000/mm3, the person may have a condition such as measles or chicken pox. The percentage of the different types of leukocytes present in the blood may also change in particular diseases, this number is important for diagnostic purposes and is called a differential count.
DID YOU KNOW? Rh is so named because the initial study was done with Rhesus monkey.
DID YOU KNOW? Leukocytes are capable of amoeboid movement and are sometimes called amoebocytes.
Related Products
WARD’s Simulated ABO and Rh Blood Typing Lab Activity
Examine the Risk of Rh Incompatibilities
Another WARD’S safety and innovation exclusive! In addition to all the blood typing exercises your students can perform with our ABO Activity, now they can go even further as they explore Rh typing as well. Using four different samples of WARD’S Simulated Blood, the class will determine each unknown sample’s blood type and Rh factor, examine the risk of Rh incompatibilities, and view red and white “blood cells” under the microscope in complete safety. It includes four simulated blood types (A, B, AB, O), two anti-sera (A, B), Rh anti-sera, a teacher’s guide, and student copymaster. Enough materials for twelve lab groups are included.
Immune Response: Antigen/Antibody Reactions Lab Activity
Explore the Importance of Blood Antigens During Pregnancy
Determine which of four possible donors could safely give blood to a patient, then develop a case history of a mother and her children to determine the safety of her pregnancy, all using WARD’S Simulated Blood. In the process, students learn to identify antigen/antibody reactions, and how those reactions affect the body’s immune response, as well as the basics of ABO and Rh blood typing. The kit contains enough materials for 12 setups, a teacher’s guide, and student copymaster.
Blood Typing Demonstration Model
Re-create the Antigen-Antibody Interactions Occurring on the Surface of Red Blood Cells
Provide a visual interpretation of a concept often difficult for students to understand. Using the model, you can demonstrate the antigen-antibody reactions that occur at the molecular level, including blood typing reactions, successful and unsuccessful blood transfusion reactions, and Rh incompatibility. The class-size model kit contains 12 erythrocytes, and six pairs each of A, B, and Rh antibodies and antigens. The demonstration size model kit contains two erythrocytes, and one pair each of A, B, and Rh antigens and antibodies.
Testing Familial Relationships Using Simulated Blood Lab Activity
Trace Blood Type Patterns Through Parents and Children
How would parents find out if their babies had been mixed up in a hospital maternity ward? That’s the scenario presented by this safe, interesting investigation. Using WARD’S Simulated Blood, students determine the blood types of two sets of parents and two children to find out which baby belongs to which family. The kit includes enough materials for six setups, a teacher’s guide, and student copymaster.
More simulated blood activities, supplies and equipment at Wardsci.com
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