Interferons (also known as IFNs) are basically proteins belonging to the vast group of glycoproteins called cytokines that are produced and discharged by various cells in reaction to the existence of pathogens, such as bacteria, viruses, tumor cells and parasites. Interferons enable the cells to communicate among them with a view to activate the immune system‘s protective defenses that get rid of the disease-bearing microbes as well as tumors.
The specific identification of interferons or IFNs is subject to their competence in interfering with the pathological reproduction inside the host cells. The other functions of interferons include triggering the immune cells like the natural killer (NK) cells and macrophages; augmenting the detection of tumor cells or infections by means of activating the regulation of T lymphocytes’ antigen performance; and enhancing the healthy cells’ capability to resist new viral infections. In effect, when one is infected, interferon production is associated to specific symptoms like fever and painful muscles.
When our body senses any indication of a viral invasion or contagion, it has the ability to activate interferon production. In turn, the interferons work to promote the making of particular proteins, thereby restraining the reproductive process of viruses within the cells in our body and, at the same time, increasing the resistance power of the body to viruses. It may be noted that these proteins are produced by our body only when required, as they have the ability to impede the regular activities like red blood cell (erythrocyte) production. Besides the humans, different animals also make cytokines in reaction to viral invasions and infections, but these proteins differ from one animal to another.
Interferons have been broadly classified under three groups – alpha interferons, beta interferons and gamma interferons. A brief discussion of each of these is presented below.
- Alpha interferons
- IFNs identified as alpha interferons comprise approximately 20 dissimilar types of proteins. Usually, the white blood cells (leucocytes) do not make alpha infernos unless they are affected by a viral infection. However, when they are infected by viruses, they release alpha proteins (interferons) into the infected cells’ external area. Subsequently, these proteins bind them to receptors located on new cells and transmit signals to those cells regarding the viruses’ presence in the neighborhood. This enables the other cells to adjust themselves to be further resistant to infections by viruses. In effect, these new cells work to modify the appearance of the genes within their nucleus. For instance, the alpha interferon has the ability to communicate with other cells to produce additional enzymes that have the aptitude to disintegrate viral products, as well as prevent the replication of the virus.
- Beta interferons
- While beta interferons have the same impact as alpha interferons, this type of protein is only made following the invasion of a cell which does not form an element of the devoted immune system, for instance, the skin cells. Infected cells producing alpha and beta interferons may possibly die following the release of these proteins.
- Gamma interferons
- Gamma interferons are produced by a number of natural killer (NK) and T-cells belonging to the immune system when these cells identify viral antigens or when different lymphocyte cells respond to any raiding stimulus. Gamma interferons work on additional cells to create added molecules on the exterior of the cell which identify antigens and supply these molecules to different cells that eliminate the antigens. This enhances the possibilities of trapping and eliminating the invading antigens even before they are able to cause any harm to our body. While the action of the gamma interferons is the same as that of the alpha interferons, these proteins work on somewhat dissimilar molecules. Gamma interferons also have the ability to transmit signals to cells indicating them to resist the viral invasions more effectively and send indications to other cells for eliminating the contagious cells with a view to prevent the spread of the virus.
It may be noted here that while their actions may be partially related, each of these three different classes of interferons have dissimilar impacts. Human interferons that are produced employing the recombinant (genetically recombined) DNA technology are available commercially. The modus operandi of the interferons is very complicated and, in fact, yet to be understood properly by scientists. Broadly speaking, interferons help the immune system to adjust itself to bacteria, viruses, cancer and several other alien substances assaulting our body. It is important to note that the interferons themselves do not eliminate the virus or carcinogenic cells; they work to perk up the response of the immune system as well as lessen the expansion of carcinogenic cells by controlling the activities of numerous genes regulating the discharge of several cellular proteins which have an effect on growth.
Function of interferons
As mentioned earlier, interferons belonging to different classes have some common impacts – all of them possess antiviral properties and are capable of combating tumours.
When cells that are infected by viruses expire owing to degeneration, they release viral particles that have the aptitude to transmit a disease to adjacent cells. Nevertheless, before its death, the infected cells are able to send a warning to nearby cells regarding the presence of viruses by means of secreting interferons. In reaction to the signal sent through the interferons, the neighbouring cells make huge amounts of protein kinase R (also called PKR), an enzyme that introduces a protein (phosphorylate) called eIF-2 reacting to any new infection by viruses. In combination with a new protein called eIF-2B, this phosporylated protein (eIF-2) develops into a dormant complex to lessen the synthesis of proteins inside the cells.
After the activation of PKR, one more cellular enzyme known as RNAse L is induced to obliterate the RNA inside the cells to lessen the synthesis of protein further in the genes of the invading virus as well as the host. Such restrained synthesis of protein within the cells eliminates the virus along with the host cells that have been infected. Furthermore, interferons encourage the manufacture of several hundred other proteins, which are collectively known as interferon-stimulated genes or ISGs that have an important function in fighting viruses. Interferons also work to restrict the spread of viruses by augmenting the actions of gene P53 that helps to eliminate the cells infected by viruses by means of inducing apoptosis (a genetically controlled process that results in the death of cells). In addition, the interferons’ effect on gene p53 is related to defensive functions of these proteins against specific forms of cancer.
Interferons have other roles too and they include enhancing the regulation of major histocompatibility (a condition wherein there are antigenic correlations that prevent the rejection of transplanted cells/ tissues) complex molecules (MHCs), MHC I as well as MHC II, in addition to augmenting the immunoproteasome actions. While increased activity of MHC I enhances viral peptide presentation to natural killer (NK) cells and cytotoxic T cells, the immunoproteasome deals with viral peptides to load them on MHC I molecules, thus enhancing the identification as well as elimination of the cells infected by viruses. Similarly, enhanced activity of MHC II molecules augments the viral peptide presentation to helper T cells, which discharge cytokines (for instance, additional interferons plus interleukins among other things) that send signals to as well as synchronize the actions of other different cells of the immune system. Some interferons like gamma interferons, work to set off other cells of the immune system, for instance, natural killer cells and macrophages, directly.
IFNs have the ability to cause tongue inflammation and result in the malfunctioning of the cells of the taste buds – sometimes completely reorganizing or destroying the taste buds.
Before concluding, we shall underline the effectiveness of different classes of interferons in brief. Alfa interferons form a part of the course of therapy for hepatitis C as well as hepatitis B. Beta interferons possess effective therapeutic antiviral attributes, in addition to assisting in the treatment of multiple sclerosis (also referred to as MS) – a health condition related to our nervous system. Gamma interferons may prove to be useful for people suffering from ailments like leprosy, skin cancer and toxoplasmosis.