In his novel, War of the Worlds, the author H.G. Wells tells about the dystopian future in which aliens would invade Earth and kill humans by the millions owing to their advanced weapons and technology, only to be defeated by bacteria to which they had no immunity. Our immunity is arguably the most complex part of our bodies. It is so adaptive that it can fight anything from bacteria to viruses to even cancer cells. The employment of immunotherapy is indeed one of the breakthroughs in modern medicine, and its benefits still surprise us to this day.
What is immunotherapy?
Immunotherapy in the broader sense refers to the treatment of medical conditions by either stimulating or suppressing the immune system. It is used in a wide variety of conditions related directly or indirectly to the immune system. Although the term can encompass the use of immunizations, they are not considered as a “therapy” but prophylaxis against infection. Nonetheless, some vaccines can be used in the treatment of cancer as will be highlighted later in the article. In its use in autoimmune diseases, it is commonly referred to as “biological therapy”.
The spectrum of immunotherapy encompasses the following:
- Immunosuppressive drugs like those used after organ transplantation and in immune disorders like systemic lupus, rheumatoid arthritis, and systemic sclerosis. Drugs like glucocorticoids act by several mechanisms to suppress inflammation and autoimmunity.
- Immune tolerance: This includes many therapies that aim at resetting your immune system so it will not react inadequately to antigens. They are used following organ transplantation, in autoimmune conditions and allergies. They include the injection of autoregulatory cells which aim at resetting the sensitivity of your cells towards your antigens, or the use of allergens in small doses in cases of seasonal allergy. Small doses of allergens allow for the immune system to become accommodated to the allergen without triggering an allergic response.
- Immune enhancement therapies: This subtype of immunotherapy is the one under much research in recent years. It includes the use of vaccines, cells, or antibodies to stimulate the immune system against specific cells, bacteria, or viruses. From the previous mechanisms, monoclonal antibodies are the most used in cancer.
The first use of monoclonal antibodies dates to 1975, and the first monoclonal antibody was Muromonab which targeted a specific cellular receptor called CD3 and was used following organ transplantation. The “CD” here is an abbreviation for cluster of differentiation which is a man-made system of using cellular receptors to differentiate different types of cells. If a cellular receptor is unique, it is assigned a different number.