Acquired immunity (adaptation): the body's resistance to infection

In addition to the general innate immunity, the human body has the ability to develop extremely strong specific immunity against specific pathogens such as viruses, bacteria, deadly toxins, and even foreign tissue from other animals. This ability is called acquired or adaptive immunity. The acquired immunity is caused by a special immune system that forms antibodies and/or activates lymphocytes to attack and destroy specific invasive microorganisms or toxins. The acquired immune mechanism, some related reactions, especially allergy, will be discussed in this chapter.

Acquired immunity can often hold extreme levels of protection. For example, certain toxins, such as paralytic botulinum toxins or tetanus toxins, can be protected against at doses 100,000 times higher than the usual lethal dose without immunity. Translate. It is for this reason that the course of treatment known as immunization is very important in protecting people against disease and against toxins, as explained later in this chapter.

Acquired immunity: humoral and cell-mediated immunity

Two basics but closely linked types of the acquired immune system occur in the body. One of which, the body develops and circulates antibodies, which are globulin molecules in the blood plasma that is capable of attacking invading agents. This type of immunity is called humoral or B-cell immunity (because B lymphocytes produce antibodies). The second type of immunity is achieved through the formation of the activation of a large number of T lymphocytes that are individually contained in the lymph node to destroy foreign agents. This type of immunity is called cell-mediated immunity or T cell immunity (because the active lymphocytes are T lymphocytes). We will see even that antibodies and active lymphocytes are formed in the lymphatic tissues of the body.

Acquired immunity is initiated by the antigen

Because acquired immunity does not develop until an invasion of an organism or foreign toxin is present, it is clear that the body must have some mechanism in place to counteract this invasion. Each poison or organism almost always contains one or more characteristic chemical compounds that are composed of different compounds. In general, these are large proteins or polysaccharides and themselves initiate the acquired immunity. That substance is called an antigen (antibody production).

For a substance with antigenic properties, it usually must have a high molecular weight such as 8000 or higher. Furthermore, antigenic processes often depend on groups of molecules that are frequently present, called epitopes, on the surface of large molecules. This factor also explains why proteins and large polysaccharides are almost always antigens because both substances have a characteristic chemical configuration.

Lymphocytes are responsible for acquired immunity

Acquired immunity is a product of lymphocytes in the body. In people with a genetic deficiency of lymphocytes or whose lymphocytes have been destroyed by radiation or chemicals, an inability to develop immunity is obtained. In the days after birth, such a person dies suddenly from a septic infection unless he or she is treated with intensive resuscitation. Hence, it is clear that lymphocytes are essential for human survival.

Lymphocytes are the most numerous of the lymph nodes, but they are also found in special lymph nodes such as the spleen, the submucosa of the intestine, the thymus gland, and the bone marrow. Lymphoid tissue is beneficially distributed in the body to prevent entry to organisms or toxins before they can spread too widely.

In most cases, invading agents first enter the liquid tissue and then migrate through the lymphatic vessels to the lymph nodes or other lymphatic tissues. Lymphoid tissue for example is the wall in the digestive tract that is immediately exposed to invading antigens from the gut. The lymphoid tissue of the throat and throat (tonsils and palate) is also intended to prevent antigens from entering the upper respiratory tract. Lymph tissue in the lymph nodes exposed to the antigen penetrates the peripheral tissues of the body, and the lymphoid tissues of the spleen, thymus gland, and bone marrow play a special role in intercepting antigenic agents. has successfully entered the circulating bloodstream.