Monoclonal antibody is a specialized type of protein molecule produced in the laboratory. Similar antibodies are produced naturally by the immune systems of animals and human beings when foreign substances, such as bacteria and viruses, invade the body. Antibodies can neutralize these substances by attaching to their antigens. Natural antibodies in blood are a mixture of many antibodies that react with many antigens, thus serving as the body’s front-line defense against disease. But solutions of monoclonal antibodies act against a single specific antigen and can be made in large quantities. They have shown promise in medical research, including the detection and treatment of cancer.
A monoclonal antibody can be produced in a test tube or culture dish by combining a tumor cell with a type of white blood cell called a B cell. The resulting hybrid cell, called a hybridoma, has properties of both the tumor cell and the B cell. Like the B cell, the hybridoma produces a specific antibody. Like the tumor cell, the hybridoma can grow and reproduce indefinitely in the laboratory. The hybridoma produces identical cells called clones, which in turn can survive in the laboratory and produce large quantities of monoclonal antibodies. Most monoclonal antibodies are produced from the B cells of laboratory animals, usually mice. Human monoclonal antibodies also have been developed. In one technique of producing human monoclonal antibodies, B cell IR (immune response) genes are inserted into a bacterial cell, which can reproduce indefinitely.
Researchers use monoclonal antibodies to attach to and identify various cell types and in certain diagnostic tests for bacteria and viruses. For example, in some allergy detection tests, monoclonal antibodies are used to identify the substance that causes the allergy.
Doctors prescribe monoclonal antibody drugs to treat certain infectious diseases. These diseases include COVID-19 and Ebola virus disease.
Some people with the hereditary disease sickle cell anemia take a monoclonal antibody drug to prevent attacks of severe pain and fever. The attacks are caused when abnormal sickle-shaped red blood cells build up in blood vessels and block the flow of blood. Certain proteins on the lining of blood vessels cause the sickle cells to “stick” to the lining. The monoclonal antibodies attach to these proteins, preventing them from sticking to the sickle cells and thus helping blood flow freely.
Monoclonal antibodies are also important in the treatment of cancer. In some cases, monoclonal antibodies can activate the body’s immune system to attack tumors. In others, the antibodies deliver tiny doses of drugs or radiation to cancer cells without harming surrounding tissues. Monoclonal antibodies carrying radiation may one day enable doctors to detect cancer when only a few malignant cells are present.
