Introduction
This topic covers immune modulation: immuno-prophylaxis and immunotherapy, passive immunization (immune sera and antibody preparations), active immunization (vaccines and immunization schedules), and immunomodulators (immunosuppressants, immunostimulants and adjuvants), with examples and applications.
Immuno-prophylaxis and immunotherapy
- Immuno-prophylaxis is the prevention of disease or infection using active or passive immunity, i.e., by vaccines (active immunization, stimulating the immune system) or immunological agents such as immune sera (passive immunization, protection via antibodies). Its purpose is to induce immunity and protect individuals from future infections or diseases.
- Immunotherapy is treatment using immunological agents: monoclonal antibodies, cytokine therapy and immune checkpoint inhibitors. It is also defined as a form of cancer treatment that boosts the immune system to fight cancer, for example by injecting monoclonal antibodies, interferon (like interferon alpha) or interleukins (like IL-2).
Passive immunity / immunization
- Passive immunity is the transfer of active immunity in the form of ready-made antibodies or pre-synthesized elements of the immune system, so that the body does not need to produce them itself. It provides rapid, temporary protection or treatment; the antibodies block the actions of an infectious agent or an immune response.
- It works quickly but does not last long, because the antibodies are naturally broken down and there are no (memory) B cells to produce more.
- Natural passive immunization: antibodies pass from mother to fetus during pregnancy or via milk.
- Artificial passive immunization is normally given by injection: purified antibody or antibody-containing serum, i.e., immune sera and antibody-containing preparations derived from the blood of immunized animals or humans.
Immune sera and other antibody-containing preparations
- Antitoxic sera: neutralize bacterial toxins (e.g., diphtheria, tetanus).
- Antibacterial sera: neutralize bacteria (e.g., anthrax, plague).
- Antiviral sera: neutralize viruses (e.g., rabies).
- Gamma globulins: broad-spectrum antibody preparations for various infections.
- Hyperimmune sera / hyperimmune globulins: blood plasma with high titers of antibody against a specific organism or antigen, prepared from donors; an example of passive immunity. Available hyperimmune globulins include those for hepatitis B, rabies and tetanus. It may be effective therapy in Ebola virus infection.
- Monoclonal antibodies (mAbs): laboratory-made, specific antibodies designed to target specific pathogens or tumor markers, used for treating infections and cancers. They recognize a single specific epitope of an antigen and are produced by hybridoma technology (B cells fused with myeloma cells give hybridomas that generate large quantities of the desired antibody). Examples include treatments for COVID-19 and cancer immunotherapies (e.g., rituximab for lymphoma, pembrolizumab). They are used to treat many diseases, including some cancers.