KEY FACTORS IN IMMUNOLOGICAL RESEARCH

 

The importance of the use of animals in immunological research and drug development

Although animals are used for many purposes, such as farming and the production of food, their use in scientific research continues to be a source of great discussion throughout the world. Many of the main advances in Immunology have arisen as a result of the use of animals. The development of transplantation surgery and the development of new medicines and vaccines would not be possible without animal research. However, many of those opposed to animal research argue that the results from animals cannot be reliably applied to humans, as we are biologically different. Anti-animal research proponents also argue that despite all the testing that is done in animals, drugs and medicines still cause adverse reactions in many people.

 

The controversy over the use of animals in research is often presented in a polarised manner, with opinions pigeon-holed as being either 'for' or 'against' their use. In reality, such views exist along a spectrum. What is self-evident is that the use of animals in immunological research has played a critical role in many landmark achievements of the past.

Developing vaccines to prevent infectious disease

The use of animal models has helped us understand how infectious diseases occur. This has led scientists to develop preventative treatments in the form of vaccines to help reduce the likelihood of someone being infected with a dangerous microbe, such as those responsible for causing polio, diphtheria, and hepatitis C. Vaccinations also offer the best solution for people in developing countries being infected HIV (the virus that causes AIDS), and the parasite responsible for causing malaria (which kills millions of people each year). Such vaccines cannot be developed without some form of animal research.

Producing drugs to manage and treat diseases

The development of several revolutionary drugs and treatments, such as insulin for diabetes, antibiotics to treat bacterial infections, and anti-retroviral drugs to delay the onset of AIDS, are all examples of medical advances that depend on animal research. Efforts to improve drugs that are already being used to treat diseases are also dependent on animal research. For example, in transplantation immunology, further research will soon help scientists produce drugs that can better prevent the all-too-common problem of rejection.

Development of new diagnostic methods

Experiments in animals have been vital for developing immunological techniques that allow diseases to be diagnosed quickly and accurately. The diagnosis of cancer relies on techniques that use immunological tools that were first discovered in animal experiments.

Treating other animals

It is not only humans that benefit from treatments derived from the use of animal research. Animals also benefit from medicines initially developed for people. These include vaccines, antibiotics, anti-parasitics and insulin. They have all been developed to protect our pets, farm animals and animals living in the wild from undue suffering and death, thus saving millions of animal lives each year.

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Alternatives to animals

Various alternatives to research with animals have been proposed, including the use of plant and tissue cultures, and computer simulations. Unfortunately, there is currently no viable replacement that would enable researchers to completely rely on non-animal methods. Plants lack a nervous and immune system and, therefore, cannot be used to help us learn about immunological phenomena. Also, computer simulations are only useful when they are based on knowledge obtained from live immunologically responsive animals. Therefore, they cannot be used as a substitute for studies in live animals.

 

Although animal laboratories are expensive to run and require a lot of work, at the present time the use of animals in immunological research is essential, and must continue so that huge advances continue. There are still many serious diseases in both humans and animals that science will be unable to cure or treat effectively unless research in animals continues.

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Types of animals used in immunological research

Many different species of animals are used for research purposes, although the majority of procedures use rats and mice (rodents).

Use of rodents in Immunology

Rodents are the main engine for immunological discoveries. They are the preferred option to test basic ideas and theories. This is partly because they are cheap, convenient, and easy to handle. There is also a plethora of rodent-specific research tools already available to help investigators study many different types of immunological phenomena. The use of rodents has led to many important advances, not least, helping scientists to identify the cells which make up the immune system and the molecules they produce.

 

Since the late-1960s, a specific type of rodent has been used in research due to its natural inability to mount an immune response to foreign substances. These rats and mice, known as 'nude rodents', have an alteration in their genes that causes them to be immunodeficient i.e. they lack an ability to protect their body and so are immunologically 'nude'. Scientists have exploited this feature to study how chemicals and drugs stimulate or suppress the immune system. Nude rodents also provide very useful models in the transplantation field, and have helped us understand the effects of drugs (including any possible side effects these drugs may have) without interference of the immune system.

 

Use of chicken eggs

Chicken eggs are typically used to produce vaccines on a large scale. The viral (pathogenic) part of vaccines is produced by injecting the virus into the eggs. The virus then replicates in large quantities within the embryo. Indeed, producing vaccines this way requires a large supply of chicken eggs, usually at the ratio of 1-2 eggs for every dose of vaccine.

 

Pigs

Pigs are used in transplantation research mainly because they have similar sized organs to humans. They also breed very rapidly, which suggests that they could [theoretically] be used to supply transplant material for humans on a large scale. This process of transplanting pig organs into humans (known as xenotransplantation) is not without problems. Since pigs are not closely related to humans, transplanting their organs into humans would induce a huge immune response, causing the organ to be automatically rejected. Therefore, scientists are currently attempting to address this by modifying pig genes to reduce the strength of the immune response and the likelihood of the transplant being rejected.

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Primates

Primates are more closely related to humans than any other animal species. This renders them very useful potential models in xenotransplantation research. However, they are more commonly used to investigate diseases such as AIDS.

 

Large animals vs rodents

The use of animals in scientific research remains a hot debate. But within the field of Immunology itself, there is also concern over the type of animals used. The current excessive use of rodents is believed by some researchers to hinder the transfer of discoveries made in basic research to their more useful clinical applications. It is claimed that experiments in rodents alone cannot find cures for all human and animal diseases. Furthermore, it is argued that they can never provide all the answers required to understand immunity properly. Indeed, the use of rodents in DNA technology research is commonly used as an example to support these claims. DNA vaccine technology was developed using mice as models and this led to clinical trials being conducted in humans. However, when tested in humans the technology failed and has yet to lead to a successful transfer to clinical medicine. Despite this, rodents continue to be used to test the concept.

 

Advantages of using larger animals

Larger animals are considered to have more things in common with humans compared to smaller animals. The use of larger animals would [in theory] provide better models for research, as:

  • their size allows for a more frequent collection of blood, which is important for analysing the rate at which the immune response changes after being challenged with an antigen;

  • larger animals are more likely to carry a zoonotic disease, which crosses the species barrier and can develop in humans;

  • the organ size of larger animals is regarded as being more suitable for developing surgical techniques for use in human organ transplantation.

Disadvantages of using larger animals

As with most tools of scientific research, there are disadvantages associated with the use of larger animal models, for instance:

  • the cost of individual animals can be high;

  • different human cultures/societies often prescribe a privileged or taboo status to some species of animals, which can prohibit their use in research;

  • larger animals are still not humans, so differences in the way their immune system works will always remain an issue.

 

Regardless of which type of animal is used for immunological research, it is clear that there must be greater dialogue between basic and clinical immunologists. Better communication between both fields would strengthen efforts to identify the most relevant animal model for use in a particular research project, and thus ultimately reduce the number of animals used.

 

Source: www.immunology.org