Phagocytic uptake of bacteria
All infectious microorganisms or foreign biological materials carry surface markers (antigens) that identify them as dangerous. Some cells of the immune system, large phagocytes called macrophages, actively absorb foreign organisms or tissues and reflect their surface markers on their own surface. Other cells called accessory T-cells (T-cells) notice these markers on macrophages and deliver information to cells of another class of lymphocytes - B cells.
There are thousands of species of B-cells, each of which is capable of producing a specific antibody to combat a particular aggressor. An auxiliary T-cell searches for a B-cell that best matches the marker information. This selected B-cell begins to reproduce, forming a huge number of copies of itself (clones). The cloned B cells then produce millions of protein molecules called antibodies.These antibodies catch the invading microorganisms and immobilize them, so that phagocytes then easily deal with them.
Some of the cloned B cells are called “memory cells”, which are stored almost forever. If another infection later arises from the same microorganisms, memory cells can be cloned to produce antibodies faster than with the first infection. That is why we have resistance to many diseases, having had them once. This is also the basis of artificial immunization (see below). Antibodies - not the only means of protection of the body by the immune system. Some T-lymphocytes - natural killers - can attack foreign organisms directly. Others are involved in the wonderful process of supervising our body cells to see if they are dangerous to the body as a whole. When normal cells of the body are attacked by viruses or DNA abnormalities leading to cancer begin to develop in them, they always put markers on their surface, meaning that something is wrong. These markers are identified by auxiliary T-cells, and antibodies or killer T-cells are called to destroy the affected cells.Without such a process of constant surveillance, many of us would have died of cancer or viral infection long ago.
This is an important class of diseases in which the immunological system of protecting the body against infection, foreign material in general, and certain types of cancer becomes in some sense flawed. The best-known example of this group of diseases is acquired immunodeficiency syndrome, AIDS (see below), but diseases associated with immunodeficiency were known in medical circles long before the onset of AIDS. They can be hereditary, that is, congenital and having a genetic origin, or acquired. Immunological mechanisms are so important for survival that large birth defects are rare.
Some deficiency in the production of immunoglobulins is normal in the early years of life, their production reaches full volume only by mature years. That is why children are so prone to infections. The child relies on antibodies that he receives from the mother before birth and with early breast milk - colostrum - after birth. Premature babies may not have time to receive a full quota of these substances from the mother.
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