All living things, including bacteria, can be attacked by pathogens, but have immune systems that fight them.
This defense system can evolve, become more advanced and sophisticated according to the evolution of the virus that causes disease.
Multicellular animals have specialized cells or tissues to deal with the threat of infectious disease. Some immune responses occur immediately to quickly contain the infectious agent. Other reactions are slower but more compatible. These self-produced defenses are called the immune system.
The human immune system is absolutely essential for the survival of mankind. Especially in the present time, when the polluted living environment is a hot issue, there are potential risks of serious disease transmission. A weakening of the immune system, even a small branch of this system, can have serious consequences, causing serious, even life-threatening infections.
SARS- CoV-2 is a new strain in the corona virus family, currently surpassing the "defense" ability of the human immune system. Photo: Japan Times.
Here's some information on what the human immune system is, where it comes from, and how it responds to pathogens.
Non-specific (innate) immunity
The human immune system consists of two levels, specific immunity and non-specific immunity. Through non-specific immunity, also known as innate immunity, the human body is able to protect itself against foreign substances that are considered harmful. These foreign substances include microorganisms (microbiology) and macromolecules such as proteins and polysaccharides when they enter the body, regardless of whether it is a physiological or pathological reaction.
Small bacteria such as viruses or larger organisms such as worms can be attacked by this system. These organisms are called pathogens when they cause disease in the host.
All animals have innate immune defenses against common pathogens. These first lines of defense include external barriers such as the skin and mucous membranes. When pathogens penetrate and reach external barriers, for example through a cut in the skin or when inhaled, they can cause serious harm.
Phagocytosis has the ability to surround pathogens, bring them into the body and neutralize them.
Specific immunity
Healthy white blood cells are vital to good health, but sometimes they fail to respond in the face of certain infectious disease threats. Specific immunity is a complement to phagocytic function and other elements of the innate immune system.
In contrast to innate immunity, specific immunity allows the body to produce a response to a specific pathogen target. Only vertebrates possess this specific immune response.
Two types of lymphocytes play an important role in specific immune responses. Lymphocytes are produced in the bone marrow, grow, and enter different cells. The two most common types are T cells and B cells.
An antigen is a foreign material that triggers a response from T and B cells. The human body has "specialized" B and T cells for a wide range of different antigens. Some people think that antigens are part of bacteria, in fact antigens can exist in other environments. A good example of this is when a person is given a blood type that doesn't match their own, which can trigger a response from the T and B cells.
You can also think in a more useful way about T and B cells. B cells, for example, have a much-needed property. They can mature and differentiate into plasma cells that make proteins, called antibodies. This protein is targeted at a specific antigen.
However, B cells alone are not strong enough to make antibodies. They need "help" from T cells to give the signal to start the process of evolution. When a B cell receives a "message" and acknowledges the antigen it is encoded to respond to, it divides and produces more plasma cells. The plasma cells then secrete large amounts of antibodies against the specific antigens circulating in the blood at that time.
A subtype of T cell is called a "T helper cell". These cells help release chemicals, providing effects such as: activating B cells to divide into plasma cells; call phagocytic cells to destroy bacteria; activate "killer" T cells. Once activated, the "killer" T cells recognize infected cells in the body and proceed to destroy them.
Regulatory T cells (also called suppressor T cells) help control the immune response. They are responsible for confirming that the germ cell has been prevented, and at the same time sending a signal to stop the "attack".
The SARS-CoV-2 virus that causes Covid-19 has the ability to invade and infect the immune system's T cells, which are responsible for eliminating invading pathogens from the body. Photo: SCMP.
Internal organs and tissues
Cells that trigger a specific immune response are also found in the internal organs of the human body. In the viscera, immune tissues allow immune cells to grow to "trap" pathogens, helping them to interact with each other and produce a specific response. Internal organs and tissues involved in the immune system include the thymus, bone marrow, lymph nodes, spleen, appendix, tonsils, and gastric mucosa (in the small intestine).
Infectious diseases and pathogens
Infection occurs when a pathogen enters the body and reproduces. This process will usually lead to an immune response. If the response is quick and effective, the causative agent will be eliminated or contained quickly so that the disease does not occur.
Sometimes viral and bacterial infections can cause some dangerous infections. People are susceptible to disease when: low or weakened immunity; The virulence of the pathogen is high or the body contains a large amount of the pathogen.
Depending on the type of infection, the symptoms may be different or similar. Fever is a common response to infection (infection). A higher body temperature can increase the immune response, creating a hostile environment for pathogens. Meanwhile, inflammation or swelling due to increased fluid in the infected area, is a sign that white blood cells are attacking, helping to release substances involved in the immune response.
Simulates SARS-CoV-2 virus entering infected cells. Photo: Sci Tech Daily.
Vaccination stimulates a specific immune response produced in B and T cells to certain pathogens. These cells persist in the body, which can lead to a quick and effective response if the body encounters a pathogen again. From there, the body produces an immune system, preventing disease.
In the current context, the human immune system has not been able to resist a strong attack from the SARS-CoV-2 virus, the causative agent of the Covid-19 pandemic. The discovery of a nCoV vaccine is expected to be a factor in ending the epidemic, but experts also suggest that the expected time to complete the vaccine may be about 12 to 18 months.
Thy An (According to History of Vaccine)
