Do you know we have warriors in our bodies to protect them from harm? Our first line of defense against numerous threats unknown and unseen to our eyes.
Every day we live is a blessing from those microscopic warriors that fight battles against harmful infiltrators that tries to enter our body. Those harmful infiltrators are called pathogens, like bacteria and viruses. The importance of the immune system has been repeatedly highlighted by the observation made by watching patients with the defective or suppressed immune system.
The body has a multilayered system to fight against these kinds of threats providing immunity. Immunity can be described as the power to provide the body resistance to diseases. There are collections of cells, molecules, tissues, and proteins that act in a kind of collaborative, coordinated system, this is called the immune system. The result is our good health.
DEFENSE AGAINST INFECTIONS
Any deficiency can cause increased susceptibility of an individual to infections.
RECOGNITION OF FOREIGN PROTEINS AND GRAFTS
They provide a tough hurdle to foreign elements in direct contact with the body.
DEFENSE AGAINST TUMORS
Many chemical components of the immune system are tumor suppressors and can even stop cancer-forming cells.
Dr. Deepanjan Roy, MBBS, MD-Medicine(PGY1) [SCB Medical College and Hospital Cuttack]
The host has a defense mechanism that consists of both innate and adaptive immune systems. Here we are going to be focusing on the innate immune system and its implications on the human body.
Innate immunity can be defined as nonspecific immunity consisting of the pre-existing defense mechanism of the body which includes the skin, mucosa as the natural barrier against pathogens, also the bodily secretions of sebum and sweat
Some of the important characteristics of the innate immune system are:
1. Innate immunity is the first line of defense of the human body.
2. It is the fast-acting immune system. It acts from the first minutes to hours of infection.
3. It comprises physical barriers like the skin and membranal (epithelial and mucosal) surfaces.
4. The mucous itself is considered to be a natural barrier against air pollutants and air-borne pathogens.
5. Enzymes comprise a great deal of the innate immune system. Tears, saliva which contains lysozymes, and amylases can build up defenses against pathogens.
6. Cells like phagocytes are the main characters that form this first wall of defense against pathogenic bacteria or viruses. Some of these cells are neutrophils, monocytes, macrophages, and so on.
7. Another important characteristic of innate immunity is inflammation-causing serum proteins. Examples of inflammation-related proteins are the Complement system and C-reactive proteins.
8. Lectins are also part of innate immunity, enzymes, and proteins like mannose-binding lectins, and ficolins. They have a similar ability of agglutination of red blood cells like an antibody. They are glycan-binding proteins that have a significant impact on cell-to-cell interaction, signaling pathways, cell developments as well as the immune system.
9. Other notable proteins and antimicrobial peptides that are part of innate immunity are defensins, cathelicidins, and many others.
10. To activate the innate mechanism and the future adaptive immune response, the body needs toll-like receptors, these help in signaling the entry of a foreign microorganism in the body and alert the defense response.
Innate immunity is characterized by the ability to recognize microbes by structures that are shared by various classes of pathogens, which are not present on the surface of the host cells. The system has evolved in such a way that it can distinguish between the microbes essential for the survival of the body.
Innate immunity has the capability of recognizing the stress molecules released by necrotic or otherwise stressed cells. Mainly those cells that are damaged. And help to eliminate them.
The receptors of innate immunity are not derived by the recombination of somatic genes but they are encoded into the germline itself. Thus, it has specificity but not variability nor diversity. Examples of innate immunity receptors are Toll-like receptors, N-Formyl methionyl receptors, and mannose receptors to name a few. All the receptors are identical and non-clonal because they arise from the same cell lineage.
The responses of the innate immune system are usually in the same way and repeat the encounter with a microbe, unlike the adaptive immunity that escalates the response with every successive encounter.