Interferons and their role in clinical medicine: From influenza treatment to therapy of complex viral and bacterial infections


It can be very hard to cope with viral infections. However, there is a “built-in” system of antiviral protection in our bodies, which are special substances – interferons. Artificial interferons and stimulators of their synthesis were created in medicine to help the body cope with the disease. This article is devoted to this subject.

Functions and mechanism of action of interferon in the human body

Interferon is a protein molecule that provides antiviral immunity. At this it has nonspecific activity, that is, it does not act on the precursor of a particular disease, but affects all viral particles in general. On the whole, interferon is a universal protector of the body, which begins to act even before the rest of the immune system starts acting [1]. Interferon preparations are even used in oncology therapy: they suppress tumor growth.

Cells produce this protective protein in response to viruses, bacteria, tumor cells, or their metabolic products. Interferon inducers can also stimulate their production. The molecules of the latter, getting into the blood and intercellular fluid, bind to the receptors of infected or damaged cells. They start a complex cascade of reactions leading to the formation of specific proteins. As a result, the cell stops reproducing viral particles, breaks down their genetic structure, and the surface of the cell becomes less permeable to intracellular parasites.

In addition to acting on the infected cells, interferons stimulate the activity of other components of the immune system, control the inflammatory response, and can even protect the body from tumors. This property is actively studied, and it has already been used to fight some types of cancer.

Types of human interferon

Interferon molecules differ in their genetic structure, the type of cell receptors they act on, even in the DNA regions that encode their composition. All interferons are divided into 3 types.

The first type includes alpha interferon, which has 13 different structural variants, as well as “beta”, “kappa”, “epsilon”, and “omega”.
The second type is represented by only one type, interferon gamma.
Relatively recently, in 2002, a third type of molecule, interferon lambda, was discovered. This is a separate family of interferons, which differs from all previous ones in genetic structure and even the type of receptors with which they interact. But in terms of their biological activity, lambda interferons are very similar to the first type.

You should not treat interferons panacea for all woes. Firstly, some viruses can suppress the formation of specific proteins inside infected cells, which significantly reduces the effectiveness of the antiviral defense.

Secondly, this is only the first “line of defense” that stimulates other links of immunity and temporarily stops the “enemy” advance through the body, so there is more time for the production of immune cells and antibodies.

Thirdly, the main mechanism of action of interferon is the suppression of development and division. At physiological doses, this effect controls the multiplication of viruses and tumor cells. But with the introduction of significant doses of foreign substances, the body’s own tissues may also be damaged, which are quickly renewed. First of all, blood cells.

Therefore, before starting treatment with interferon drugs, you need to carefully study the benefits and possible harm from taking them.

The use of interferon analogs in medicine

Medicines based on interferon have proven their effectiveness in the treatment of a wide range of diseases: herpes infections, HPV, acute and chronic forms of viral hepatitis, multiple sclerosis, lupus, influenza, and many other viral and bacterial infections. Interferon is also used in the treatment of oncological diseases, as well as AIDS. And this is done despite the fact that it was discovered quite recently by the standards of medicine. This happened in 1957 when conducting experiments on mice. Scientists noticed that animals infected with one virus became immune to another viral disease. This phenomenon was called interference, and the substances that contributed to it were called interferons. It turned out that interferons are produced not only in mice but also in all mammals, including humans. This is how the scientists started studying the possibility of industrial production of substances with antiviral effect.

However, the use of interferons was limited for a long time due to the imperfection of the procedure for their production. Isolation of this substance from the blood of a human donor was a difficult, expensive, and ineffective procedure.

Figures and facts

1 liter of donor blood contains only 1 μg of interferons (IFNs). Approximately this amount of IFNs is needed to make just one dose of the drug. And a course of treatment of severe viral diseases such as hepatitis requires about 150 doses.

In 1980, in Japan, a specially grown culture of lymphoblastic cells was used for the production of interferon for the first time. In 1981, a culture of yeast fungi was used instead of human cells in the United States. With the help of genetic engineering, a gene was introduced into the genome that encodes the production of an interferon molecule. This made it possible to significantly simplify the production of the drug.

According to the method of production, there are four main varieties of this drug: leukocyte, lymphoblastoid, recombinant, and pegylated.

Leukocyte interferon is obtained from the blood of donors. In order to enhance the production of the necessary substances, cells are pre-stimulated most often with the help of non-pathogenic viruses – such particles that cannot cause disease, but are perceived by the cells of the immune system as “signaling”.

After preparation is obtained, it is purified and concentrated. It can include all types of interferons and other biologically active substances. This capability is a benefit and a drawback at the same time. Such a drug has a high potential for biological action but features a high probability of side effects when administered intramuscularly.

Lymphoblastoid interferon is not obtained from a human donor, but from a culture of lymphoblastic cells, which are also treated with substances that stimulate the immune response. Such drugs contain a certain ratio of different types of interferon and do not often cause side effects.

Recombinant drugs are obtained from a culture of cells of bacteria or fungi, into which a segment of a human gene has been specially introduced. Interferon obtained in this way may differ slightly in structure from the “natural” human interferon. Such drugs retain antiviral activity, but it is difficult to achieve immunity stimulation with their help.

Pegylated or PEG interferons are recombinant protein molecules combined with polyethylene glycol. This compound increased the duration of the action of interferon in the body.

For instance, if the standard recombinant interferon is used for the treatment of viral hepatitis C, it needs to be administered three times a week, then pegylated interferon should be used once at the same time.

PEG is soluble in water, does not enter into biological reactions in the body, and does not induce an immune response. When PEG is attached, the interferon molecule increases significantly in size. And this, in turn, increases the half-life of the drug.

Interferon-based drugs: indications and contraindications for their use

It’s not possible to combine interferons into homogeneous groups according to the method of production, release forms, and indications. Each drug has its own characteristics of use and effectiveness in certain diseases. Depending on the degree of purification and other factors, some preparations with the same type of immunoglobulin can be used only locally, and some can be used as injections.

For example, drugs such as “Inferon” and “Alfaferon” belong to the group of leukocyte interferons. At the same time, “Inferon”, according to the instructions, is used intramuscularly for unspecified viral diseases and for immunotherapy. Alfaferon is also injected into the muscle, but at the same time, it is already used to treat hepatitis, mycosis, and even some types of cancer. And “Human leukocyte interferon” is used for topical application, nasal instillation, and inhalation.

Therefore, one should focus not only on the general characteristics of a group of substances when choosing an interferon drug but first of all on the doctor’s recommendations and instructions for the use of a particular drug.

Interferon in the form of injections is used for systemic diseases such as hepatitis, tumors, or multiple sclerosis. The drug in the form of nasal drops is suitable for the treatment of rhinosinusitis and the prevention of ARVI. Eye drops will help patients diagnosed with conjunctivitis. Suppositories can be used for many diseases, including in children as well. And the gel is suitable for lubricating the nose or skin.

One of the most homogeneous groups at the moment are pegylated interferons. There are two main classes of drugs with proven efficacy – peginterferon alfa-2a and peginterferon alfa-2b. The representative of the first class – “Pegasys”, the second – “PegIntron”. Both drugs are intended for subcutaneous use (under the skin), once a week and used only for the treatment of chronic viral hepatitis B and C.

Recombinant interferon presents one of the most numerous groups of drugs by trade names. This includes drugs such as “Reaferon”, “Viferon”, “Ingaron”, “Interferal” and others. These drugs come in various forms for topical use and for injection. Each drug has its own list of indications in the instructions, but in general, these are viral and bacterial infections.

Interferons protect the body from viruses, bacteria, and tumor cells. They have complex biological effects. But modern medicine has learned to create similar substances and use them. However, choosing the right drug is a task that only a doctor can solve.

What are interferon inducers

There are drugs that do not only add a “portion” of interferons to the body but stimulate the growth of the body’s own protective proteins. Such drugs are called interferon inducers. Some drugs stimulate the production of certain interferons, while others increase the production of all types of interferons. The last group of drugs includes “Amiksin”. The active ingredient of “Amiksin” is tilorone, the main function of which is to stimulate the production of interferon in the body . The compound has been used in clinical practice for over 30 years and is one of the most studied interferon inducers. It is indicated for the prevention and treatment of influenza and other acute respiratory viral infections, as well as the treatment of herpes infections (as part of complex therapy).

The advantages of this drug are the maximum production of interferon since the first day of administration and the activation of four types of interferons. An increase in the concentration of interferons can be achieved after 4 hours in some organs.

All interferon inducers have individual characteristics, indications, and contraindications. Therefore, the drug must be chosen carefully, only after reading the instructions. Special care should be taken when choosing medicine for children. There are separate forms of release developed for little ones.

You should never self-medicate. The medication should be taken only after consultation with your doctor.

P.S. Amixin is an interferon inducer manufactured by the Russian pharmaceutical company Pharmstandard-Tomskkhimfarm. The drug was developed at the Gamaleya Research Institute of Epidemiology and Microbiology, Research Institute of Flu.

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