Immunity is a word that for most people is almost magical. The fact is that each organism has its own genetic information peculiar only to it, therefore, each person's immunity to diseases is different.
So what is immunity?
Surely everyone who is familiar with the school curriculum in biology roughly imagines that immunity is the body's ability to protect itself from everything alien, that is, to resist the action of harmful agents. Moreover, both those that enter the body from the outside (microbes, viruses, various chemical elements), and those that are formed in the body itself, for example, dead or cancerous, as well as damaged cells. Any substance that carries alien genetic information is an antigen, which literally translates as “against genes”. Nonspecific and specific immunity is ensured by the holistic and coordinated work of the organs responsible for the production of specific substances and cells capable ofto recognize what is for the body and what is alien, and also adequately respond to the invasion of the foreign.
Antibodies and their role in the body
The immune system first recognizes the antigen and then tries to destroy it. In this case, the body produces special protein structures - antibodies. It is they who stand up for protection when any pathogen enters the body. Antibodies are special proteins (immunoglobulins) produced by leukocytes to neutralize potentially dangerous antigens - microbes, toxins, cancer cells.
By the presence of antibodies and their quantitative expression, it is determined whether the human body is infected or not, and whether it has sufficient immunity (nonspecific and specific) against a particular disease. Having found certain antibodies in the blood, one can not only conclude the presence of an infection or a malignant tumor, but also determine its type. It is on the determination of the presence of antibodies to pathogens of specific diseases that many diagnostic tests and analyzes are based. For example, in an enzyme-linked immunosorbent assay, a blood sample is mixed with a pre-prepared antigen. If a reaction is observed, it means that antibodies to it are present in the body, therefore, this agent itself.
Varieties of immune protection
According to their origin, the following types of immunity are distinguished: specific and non-specific. The latter is innate and directed against any foreign substance.
Non-specific immunity is a complex of protective elements of the body, which, in turn, is divided into 4 types.
- To mechanical elements (skin and mucous membranes, eyelashes, sneezing, coughing appear).
- To chemical (sweat acids, tears and saliva, nasal secretions).
- To humoral factors of the acute phase of inflammation (complement system; blood coagulation; lactoferrin and transferrin; interferons; lysozyme).
- To cellular (phagocytes, natural killers).
Specific immunity is called acquired, or adaptive. It is directed against a selected foreign substance and manifests itself in two forms - humoral and cellular.
Specific and non-specific immunity, its mechanisms
Let's consider how both types of biological protection of living organisms differ from each other. Nonspecific and specific mechanisms of immunity are divided according to the reaction rate and action. Factors of natural immunity begin to protect immediately, as soon as the pathogen penetrates the skin or mucous membrane, and do not preserve the memory of interaction with the virus. They work throughout the entire time of the body's battle with the infection, but especially effectively - in the first four days after the penetration of the virus, then the mechanisms of specific immunity begin to work. The main defenders of the body against viruses during the period of nonspecific immunitybecome lymphocytes and interferons. Natural killer cells identify and destroy infected cells with the help of secreted cytotoxins. The latter cause programmed cell destruction.
As an example, consider the mechanism of action of interferon. During a viral infection, cells synthesize interferon and release it into the space between cells, where it binds to receptors on other he althy cells. After their interaction in cells, the synthesis of two new enzymes increases: synthetase and protein kinase, the first of which inhibits the synthesis of viral proteins, and the second cleaves foreign RNA. As a result, a barrier of uninfected cells is formed near the focus of the viral infection.
Natural and artificial immunity
Specific and non-specific innate immunity is divided into natural and artificial. Each of them is active or passive. The natural comes naturally. Natural active appears after a cured disease. For example, people who had the plague did not become infected while caring for the sick. Natural passive - placental, colostral, transovarial.
Artificial immunity is detected as a result of the introduction of weakened or dead microorganisms into the body. Artificial active appears after vaccination. An artificial passive is acquired with a serum. When active, the body creates antibodies on its own as a result of disease or active immunization. It is more stable and durablecan persist for many years and even a lifetime. Passive immunity is achieved with the help of antibodies artificially introduced during immunization. It is shorter, works a couple of hours after the introduction of antibodies and lasts from several weeks to months.
Specific and non-specific immunity differences
Non-specific immunity is also called natural, genetic. This is a property of an organism that is genetically inherited by members of a given species. For example, there is human immunity to dog and rat distemper. Congenital immunity can be weakened by irradiation or starvation. Nonspecific immunity is realized with the help of monocytes, eosinophils, basophils, macrophages, neutrophils. Specific and non-specific factors of immunity are also different in time of action. Specific manifests itself after 4 days during the synthesis of specific antibodies and the formation of T-lymphocytes. At the same time, immunological memory is triggered due to the formation of T- and B-cells of memory for a specific pathogen. Immunological memory is stored for a long time and is the core of a more effective secondary immune action. It is on this property that the ability of vaccines to prevent infectious diseases is based.
Specific immunity aims to protect the body, which is created in the process of development of an individual organism throughout its life. If an excessive amount of pathogens enters the body, it can be weakened, although the disease will proceed in a milder form.
What is the immunity of a newborn baby?
A newly born baby already has non-specific and specific immunity, which is gradually increasing every day. The first months of a baby's life are helped by the mother's antibodies, which he received from her through the placenta, and then receives with breast milk. This immunity is passive, it is not persistent and protects the child up to about 6 months. Therefore, a newborn baby is immune to infections such as measles, rubella, scarlet fever, mumps and others.
Gradually, as well as through vaccination, the child's immune system will learn to produce antibodies and resist infectious agents on its own, but this process is lengthy and very individual. The final formation of the child's immune system is completed at the age of three. In a younger child, the immune system is not completely formed, so the baby is more susceptible than an adult to most bacteria and viruses. But this does not mean that the body of a newborn is completely defenseless, it is able to withstand many infectious aggressors.
Immediately after birth, the baby encounters them and gradually learns to exist with them, producing protective antibodies. Gradually, microbes populate the baby's intestines, dividing into useful ones that help digestion and harmful ones that do not show themselves in any way until the balance of microflora is disturbed. For example, microbes settle on the mucous membranes of the nasopharynx and tonsils, and protective antibodies are produced there. If an infection entersthe body already has antibodies against it, the disease either does not develop, or passes in a mild form. Preventive vaccinations are based on this property of the body.
Conclusion
It should be remembered that immunity is nonspecific and specific - it is a genetic function, that is, each organism produces the number of various protective factors necessary for it, and if this is enough for one, then it is not for another. And, conversely, one person can completely get by with the necessary minimum, while another person will need much more protective bodies. In addition, the reactions occurring in the body are quite variable, since the work of the immune system is a continuous process and depends on many internal and external factors.
