Immunity Types: innate and adaptive, active and passive

Immunity – (Latin immunitas – liberation) – protection of the organism from genetically alien organisms and substances, which include microorganisms, viruses, worms, various proteins, cells, including the organism’s own altered cells.

Immunology is the science that studies immunity.

The immune response is the body’s response to the introduction of foreign agents.

Antigen – any foreign substance or organism.

Antibody – a substance of the body that recognizes antigens.

Antibodies (immunoglobulins) are a special class of glycoproteins present on the surface of B-lymphocytes as receptors. Reacting to the presence of antigen, they detach from B-lymphocyte membrane and are present in blood serum and tissue fluid in the form of soluble molecules (antibodies). Antibodies are able to selectively bind to specific types of foreign molecules, which are therefore called antigens.

Antigens are used by the immune system to identify and neutralize foreign objects such as bacteria and viruses.

Antigens are usually proteins or polysaccharides and represent parts of bacterial cells, viruses and other microorganisms.

Non-microbial antigens include plant pollen proteins, egg proteins and tissue and organ transplant proteins, as well as blood cell surface proteins from blood transfusions.

Allergens are antigens that cause allergic reactions.

History of immunity research

The foundation of immunology was laid by the invention of the microscope, which made it possible to detect the first group of microorganisms – pathogenic bacteria.

In the late 18th century, an English country doctor, Edward Jenner, reported the first successful attempt to prevent disease through immunization. His approach grew out of the observation of an interesting phenomenon: milkmaids often contracted cowpox and subsequently did not get smallpox. Jenner injected a young boy with pus taken from a pustule (abscess) of cowpox and verified that the boy was immune to smallpox.

Jenner’s work gave rise to the study of the theory of the microbial origin of diseases in the 19th century by Pasteur in France and Koch in Germany. They found antibacterial factors in the blood of animals immunized with microbial cells.

Louis Pasteur successfully grew various microbes under laboratory conditions. As is often the case in science, the discovery was made by accident while culturing cholera pathogens in chickens. While working, one of the cups with microbes was forgotten on the laboratory table. It was summer. The microbes in the cup had been heated several times in the sunlight, dried out, and lost their ability to cause disease. However, the chickens that received these incomplete cells proved immune against a fresh culture of cholera bacteria. Not only did the weakened bacteria not cause the disease, but, on the contrary, they gave immunity.

In 1881 Louis Pasteur developed principles for creating vaccines from weakened microorganisms in order to prevent the development of infectious diseases.

In 1908 Ilya Ilyich Mechnikov and Paul Ehrlich were awarded the Nobel Prize for their work on the theory of immunity.

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И. I. I. Mechnikov created the cellular (phagocytic) theory of immunity, according to which phagocytosis plays the decisive role in antibacterial immunity.

At first I. I. Mechnikov as a zoologist experimentally studied marine invertebrates of the Black Sea fauna in Odessa and noticed that certain cells (coelomicytes) of these animals absorb all foreign particles (including bacteria) penetrating into the internal environment. He then saw an analogy between this phenomenon and the absorption of microbial bodies by the white blood cells of vertebrate animals. I. I. Mechnikov realized that this phenomenon was not the feeding of a given single cell, but a protective process in the interests of the whole organism. The scientist called the protective cells acting in this way phagocytes – “devouring cells”. I. I. Mechnikov was the first to consider inflammation as a protective rather than destructive phenomenon.

At the beginning of the 20th century, most pathologists opposed Mechnikov’s theory, since they considered leukocytes (pus) as pathogenic cells and phagocytes as carriers of infection throughout the body. However, I.I. Mechnikov’s work was supported by Louis Pasteur. He invited I.I. Mechnikov to work at his institute in Paris.

Paul Ehrlich discovered antibodies and created the humoral theory of immunity, having established that antibodies are transmitted to the child with the breast milk, creating passive immunity. Ehrlich developed a method of producing diphtheria antitoxin, thanks to which millions of children’s lives were saved.

Ehrlich’s theory of immunity suggests that there are special receptors on the surface of cells that recognize foreign substances (antigen-specific receptors). When confronted with foreign particles (antigens), these receptors detach from the cells and are released into the blood as free molecules. In his article, P. Ehrlich referred to antimicrobial substances in the blood with the term “antibody,” as bacteria at the time were called “microscopic cells.”

Ehrlich assumed that even before contact with a particular microbe, the body already has antibodies in a form which he called “side chains”. It is now known that he was referring to lymphocyte receptors for antigens.

In 1908. Paul Ehrlich was awarded the Nobel Prize for the humoral theory of immunity.

A little earlier Karl Landsteiner had first proved the existence of immunological differences between individuals within the same species.

Peter Medawar proved the amazing accuracy of recognition of foreign proteins by immune cells: they are able to distinguish a foreign cell by only one altered nucleotide.

Frank Burnett postulated the position (Burnett axiom) that the central biological mechanism of immunity is the recognition of one’s own and another’s.

In 1960 Peter Medawar and Frank Burnett received the Nobel Prize in Physiology or Medicine for the discovery of immunological tolerance (lat. tolerantia), which is the recognition and specific tolerance of certain antigens.

Destruction of genetically modified cells

One function of the immune system is the destruction of genetically altered (mutant) cells in the body. In the process of cell division errors constantly occur and one out of a million cells formed becomes mutant, i.e. genetically alien. There must be more than 10 million mutant cells in the human body at any given time due to mutations. Mutations lead to changes in cell functions. Most mutant cells are unable to perform their functions, and many get out of the body’s control (for example, when apoptosis is disrupted) and become cancer cells. The emergence of such cells can lead to serious diseases and death of the body.

One of the immune mechanisms carried out by lymphocytes (NK-lymphocytes) is aimed specifically at destroying cancer cells.

Types of immunity

Immunity can be divided into cellular and humoral

Immunity Types: innate and adaptive, active and passive
Cellular and humoral immunity

All the different forms of immune response can be divided into two types: innate immunity and acquired immunity.

Immunity Types: innate and adaptive, active and passive
Classification of immunity

Acquired immunity is specific individual immunity, that is, it is immunity that exists specifically in certain individuals and to certain pathogens or agents.

The main characteristics of acquired immunity are specificity and immunological memory. The more often the organism encounters a pathogen, the faster and more active the production of antibodies, hence the stronger the protection.

Congenital immunity from birth (even before the first encounter with the antigen) protects the body against everything foreign, i.e. it is not specific.

Thus, repeated encounter with this or that pathogenic microorganism does not lead to changes in the innate immunity, but increases the level of acquired immunity.

Veronika Sergunina
Veronika Sergunina
7 years of experience in nutritional medicine Nutritionist, Child Nutritionist
Congenital immunity is activated more rapidly upon the first occurrence of the pathogen, but it recognizes the pathogen with less precision. It does not respond to specific antigens, but to certain classes of antigens characteristic of pathogens (viral capsid proteins, products of worm metabolism, etc.).

Congenital immunity can be hereditary (species) and individual.

Hereditary (species) immunity is the immunity of all members of a given species to a certain antigen, acquired in the process of evolution:

  • diseases that humans contract but animals and birds do not (measles, smallpox, leprosy, viral hepatitis, cholera, gonorrhea, dysentery, typhoid, etc.);
  • diseases that afflict animals but do not afflict humans (plague of cattle, pyroplasmosis of dogs); 
  • diseases that affect birds but do not affect humans (chicken cholera);
  • diseases that affect animals and humans, but do not affect birds (anthrax, rabies, etc.).
  • Individual innate immunity is determined by those characteristics that are passed on to the organism with the parental genes and during embryonic development.

During embryonic development, the mother’s antibodies are passed on to the fetus through the placenta to counteract infections. The transmission of antibodies from the mother to the baby takes place mainly in the last trimester of pregnancy.

Immunity is divided into natural and artificial immunity.

Natural immunity arises on its own during the life of the body.

Natural immunity is divided into active immunity (after diseases) and passive immunity (e.g. with mother’s milk).

Up to 6 months of age the baby is protected by antibodies passed from the mother with the breast milk. Exclusive breastfeeding is therefore important. The mother’s immunity protects the baby. Babies who are artificially fed are poorly protected, because they have few antibodies of their own. Only at 6 months of age does the body start producing its own antibodies. The child’s own immunity is formed only at the end of the first year of life.

The body acquires artificial immunity through the use of medicines (vaccines and serums).

A vaccine is a medicine that contains weakened or killed germs.

The vaccine is given to a perfectly (!) healthy person to prevent future illness.

Serum – medical preparation of blood plasma without fibrinogen, containing ready-made antibodies to a certain pathogen (infecting microorganism). Serum is obtained from the blood of an animal (cow, horse, etc.) infected with the disease.

A serum with foreign antibodies is injected into a sick person when the body is unable to produce enough antibodies.


  1. – How the immune system works
  2. – Immunity Types
  3. – Immunity (medical)

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