When we are healthy, we often ignore the "invisible guardian" of the immune system, which is committed to protecting human health all the time. Our living environment is full of bacteria and viruses that cannot be distinguished by the naked eye. They are eyeing up and waiting for an opportunity to invade the human body at any time. Without the protection of the immune system, even a speck of dust can kill people.
Antibodies are in the shape of "sub", and they will bind together immediately after recognizing antigens.
The immune response of human body is very complex, which is accomplished by many cells in cooperation.
The human immune system is complex and effective. When bacteria, viruses and other pathogenic microorganisms invade the human body, macrophages will immediately go out to hunt down the invaders and devour them. Macrophages patrol the human body all the time, just like scavengers. As long as you meet cells that are not your own body, they will all be swallowed up. This is the so-called nonspecific immunity. Macrophages will also "embed" the decomposed invader fragments on the cell surface, that is, antigens, indicating that they have swallowed the invading germs, and "notify" the T cells in the immune system, so that the immune system can "heavyweight" prepare for an all-round war with the invaders.
T cells are divided into three categories: killer T cells, helper T cells and regulatory T cells. Killing T cells can destroy infected human cells and inhibit the spread of intruders. The helper T cells are responsible for summoning more killer T cells to fight, and informing B lymphocytes in time. B lymphocytes can produce specific antibodies and act as "shells" against intruders. The role of regulatory T cells is to tell B cells and other T cells when to end the battle. T lymphocytes and B cells have specificity and memory. When the first infection is suppressed, the immune system will record the information of the intruder in detail. If they attack again, the immune system can react quickly and destroy the invaders in one fell swoop.
Why can vaccines protect the human body from pathogenic microorganisms? This is the use of the immune system can "remember" this feature. Vaccine is a biological product made by artificial attenuation, inactivation or genetic engineering of pathogenic microorganisms. Vaccines can stimulate the immune system, but they are harmless to the human body. As an intruder, it conducts a "drill" with the human immune system before actual combat, which is helpful for the human immune system to identify and destroy vaccines that are very similar to pathogenic bacteria but have no lethality as soon as possible, so that a large number of protective substances, such as immune hormones, active physiological substances and special antibodies, can be stored in the human body, and the immune system can remember this pathogenic bacteria.
When one day "fighting" with pathogenic bacteria, the immune system will follow its existing memory and make protective substances more quickly to prevent the harm of pathogenic bacteria. The emergence of vaccinia vaccine completely eliminated smallpox virus that threatened human beings for thousands of years, and ushered in the first victory of human beings against viruses with vaccines; Vaccines have also greatly reduced the number of patients with polio, hepatitis B and other diseases.