Immune serum
An immune serum is a purification of specific antibodies that are obtained from the blood serum of immunized other mammals (heterologous immune serum) or humans (homologous immune serum). One speaks specifically of vaccination serum when the immune serum is obtained for the purpose of passive vaccination . In connection with the treatment of poisoning (for example snakebites, etc.), however, the term antiserum is used. Healing serum is another, outdated term for this particular type of serum. Other areas of application are the treatment of infectious diseases as well as research and diagnostics in medicine and molecular biology .
Manufacturing
For a heterologous immune serum, animals - often horses , cattle , sheep or rabbits - are vaccinated with the respective antigen . An antigen is a foreign protein , for example a pathogen or part of it, or a poison, which the immune system recognizes as a potential enemy and fights it. As part of this immune response , specific antibodies are formed against this exogenous substance. This immunization is repeated several times in order to increase the concentration of the specific antibodies. In the case of poisons (for example from poisonous snakes , scorpions or spiders ), a small dose is started and gradually increased. The animals' immune system forms antibodies without becoming dangerously ill.
The antibodies in homologous immune sera from humans, on the other hand, usually originate from natural contact with these antigens (for example as a convalescent serum after illnesses that have successfully healed).
The blood serum prepared from the blood after immunization now contains these specific antibodies. The immunoglobulins in the blood serum are purified by further biochemical processes. The antibodies administered in passive vaccination (see below) are usually made from human blood. The antibodies are extracted from up to 20,000 pooled (poured together) blood supplies. This carries a certain risk of the transmission of diseases, especially those whose mode of transmission is not known (e.g. BSE ). Known diseases ( HIV ) could also be transmitted if not handled properly. Animal antibodies that are to be used in humans (e.g. against snake venom , botulism, etc.) are treated with fermentation in order to prevent an immune reaction against these proteins. The finished immune serum is then kept ready or used in appropriate research facilities, clinical departments and tropical institutes.
Use in medicine as a passive vaccination
The passive vaccination was introduced in 1890 by Emil von Behring and Kitasato Shibasaburō when they were developing a cure for diphtheria . With passive vaccination, the antibody is injected directly. This has the advantage that the organism does not first have to develop antibodies itself, which can take up to a week or, in the case of a poison, can overwhelm the immune system depending on the concentration, but the injected antibodies recognize and mark the pathogens immediately, so that the immune system of the patient can then react to the signals of the antibodies and render the foreign body harmless. The contamination of blood sera of horse Jim led to the testing of vaccines for other pathogens .
As a rule, such a passive vaccination lasts only a few weeks to months, then the "borrowed" antibodies are excreted or broken down and the organism is endangered again by a new infection by the same pathogen, since the immune system is not stimulated by this form of rapid treatment was to develop one's own immune memory. The passive vaccination is therefore only an emergency measure if there has already been contact with the pathogen or poison in question ( post- exposure prophylaxis ). An example of this is a suspected tetanus infection . If a patient with an unclear vaccination status has a contaminated wound, he will receive a passive vaccination in addition to the active vaccination to rule out infection. The same applies to rabies in dog bites.
Use in research and diagnosis
The high specificity with which antibodies recognize their antigen is used in medicine and biology to make the antigen, in the vast majority of cases a protein, visible. The production of polyclonal antibodies from immune sera takes place as described above (in contrast to the production of monoclonal antibodies ).
The antibodies obtained in this way are either coupled (labeled) directly with an enzyme (converts a substrate into color or chemiluminescence ), with fluorescent dyes or with radioactive isotopes, or with a secondary antibody that binds to the first (primary antibody) and is labeled accordingly, proven.
- Immunohistochemistry - Detection of an antigen on a cell surface, in the cytoplasm or in the cell nucleus by means of antibodies on tissue thin sections (cryo or paraffin) and thus indirect detection of cell types, differentiation stages, etc.
- ELISA : Quantification of antigens or antibodies in serum, cell culture supernatants, etc. using enzyme-linked antibodies
- ELISPOT : Detection of antibody- or antigen-secreting cells (plasma cells, cytokine-secreting cells) using enzyme-linked antibodies
- FACS : Quantification of cells using fluorescence-coupled antibodies against antigens on the cell surface, in the cytoplasm or in the cell nucleus
- Western blot
- Supergelshift (see also EMSA )
- pregnancy test
- Phage display
- Drugwipe test
- Abzyme