Lab 9: ELISA and Blood Typing
Abstract: The immune system consists of specialized cells and chemicals that work to protect the body against harmful pathogens, such as bacteria, viruses, or parasites. The immune system includes both a nonspecific, innate component and a specific, acquired component. The presence of specific antibodies in a person’s serum and lymph indicate that his immune system has been activated. Immunoassays are used in medical laboratories to detect viral infections, such as HIV, influenza, and rubella. These assays detect either the amount of antibody or the amount of antigen present in a solution. The amount of antibody present is reported as an antibody titer, which indicates how much antibody has been produced by an individual in response to the viral agent. For example, pregnant women will have their rubella titer determined to assure that they have adequate protection against rubella (German measles). These immunoassays can also be used to detect the presence of specific drugs, hormones, or other chemicals in solution. While learning about immunoassays, you will have the opportunity to learn some basic principles of how the immune system functions in the human body. Determining blood type relies on detecting the presence or absence of antigens (A, B, and Rh factor) on the surface of a person’s red blood cells. Antibodies that bind to these antigens will cause the red blood cells to agglutinate (clump together), which is easily visible. If the red blood cells lack a particular antigen, the antibody against the antigen has nothing to bind to and the red blood cells will not agglutinate.