Description: An antigen is a substance that triggers an immune response in the body. Generally, antigens are proteins or polysaccharides found on the surface of pathogens such as bacteria, viruses, and fungi, as well as on tumor cells or transplanted tissues. When an antigen enters the body, the immune system recognizes it as foreign and activates a series of defense mechanisms, including the production of antibodies by B cells and the activation of T cells. Antigens can be classified into two main categories: exogenous antigens, which come from outside the body, and endogenous antigens, which are produced by the body itself. The specificity of the immune response to a particular antigen is crucial for the effectiveness of the immune system, as it allows the body to identify and eliminate specific threats. Additionally, antigens are essential in vaccine development, where harmless antigens are introduced to prepare the immune system for future infections. In the field of bioinformatics, the analysis of antigens and their interaction with the immune system has become a crucial area of study, enabling the design of new therapies and vaccines through the use of computational tools to predict the structure and function of antigens.
History: The term ‘antigen’ was introduced in the 1900s, although the understanding of immune mechanisms dates back to early observations of immunity. In 1880, Louis Pasteur demonstrated that immunity could be induced through vaccination, laying the groundwork for the study of antigens. Throughout the 20th century, research on antigens expanded, especially with the development of techniques such as electrophoresis and immunodiffusion, which allowed for the identification and characterization of specific antigens. In the 1970s, the discovery of monoclonal antibodies revolutionized the field, enabling the production of antibodies specific to particular antigens, facilitating the diagnosis and treatment of various diseases.
Uses: Antigens have multiple applications in medicine and biotechnology. They are used in vaccine development, where antigens are introduced to stimulate an immune response without causing disease. They are also fundamental in diagnostic tests, such as antigen tests for detecting viral infections, such as HIV or SARS-CoV-2. Additionally, antigens are used in immunotherapy treatments, where therapies are designed to direct the immune response against specific cancer cells.
Examples: An example of an antigen is the hepatitis B virus capsid protein, which is used in the vaccine against this disease. Another example is tumor antigens, such as prostate-specific antigen (PSA), which is measured in blood to assist in the diagnosis and monitoring of prostate cancer. Additionally, rapid antigen tests for COVID-19 use antigens from the SARS-CoV-2 virus to detect active infections.
