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This phenomenon is called immune memory. When an antigen makes contact for the first time with cells of the humoral immune system, B lymphocytes that are producers of specific immunoglobulins against that antigen multiply and in days synthesize their antibodies. This is called primary response. Some of these specific B lymphocytes remain in the circulation for a long time, sometimes during the entire life of the individual, and they become the memory cells of the immune system. When the body is exposed in the future to the same antigen the production of antibodies will be faster and more intense since the immune system is already prepared to react against that antigen. This is called the secondary response.

The main leukocytes that generally multiply and participate in the defense against viral infections are the lymphocytes. In this type of inflammation the blood level of these cells are increased, a clinical condition known as lymphocytosis. 

Pus is a residual of the inflammatory reaction. It contains a mixture of fragments of dead leukocytes, infectious agents (generally bacteria) and tissues.

1. Acetobacter, Nitrococcus

2. Rhizobium

When some tissue injury occurs histamine and other vasoactive substances (called mediators of inflammation) are released, they cause vasodilation and the blood flow to the affected site increases. Granulocyte leukocytes present in the blood are attracted to the site of the injury by substances known as chemotactic factors also released by the injured tissue and by the active granulocytes in the area. The granulocytes exit the capillaries by diapedesis, i.e., using pseudopods. Macrophages present in the region are activated too. These cells flood the extracellular space of the affected area trying to kill or eliminate harmful agents, to prevent tissue necrosis and to isolate the damaged tissue.

In the tissue region where inflammation occurs bacterial toxins, cytokines, prostaglandins, interleukins and endothelins are released. These substances gain the circulation and reach the central nervous system which then commands the increase of the body temperature.

Inflammation is the initial response of the unspecific defense system versus aggressions against the body (the aggressions may be caused by infectious parasites, chemical contamination, trauma, physical agents like heat and fire, autoimmunity, etc.). During inflammation a series of unspecific leukocytes present in the circulation are attracted to the injury site in an attempt to destroy harmful agents and to isolate the affected region of the tissue.

The main leukocytes that generally multiply and participate in the inflammation reaction against bacterial infections are the neutrophils. In this type of inflammation the blood level of these cells are increased, a clinical condition known as neutrophilia.

In the bacterial inflammation fragments of dead bacteria, dead neutrophils and tissues form the pus.

Vaccines are controlled inoculations of fragments of infectious agents or of inactive infectious agents to induce the primary immune response, the formation of specific memory B lymphocytes against the antigen. Therefore the organism produces immunoglobulins and becomes prepared to destroy antigens when exposed to new infections by those agents. 

In allergies the humoral immune system is sensitized (makes antibodies and specific memory B lymphocytes) against some common environmental substances wrongly recognized as antigens. For example, pollen-derived substances, dust particles, compounds present in foods or in medicines, etc. may be recognized as antigens triggering the primary response and creating an immune memory against them that then become causes of allergy. The more the individual is exposed to those substances the more intense is the immune reaction.

The IgE antibodies that cause allergy bind to receptors of leukocytes called mastocytes whose cytoplasm is full of histamine granules. The antibodymastocyte bond causes these cells to release a great amount of histamine in the circulation, stimulating inflammation and generating the allergic symptoms and signs. For this reason allergy is treated with antihistamines, drugs that block the histaminic reaction. Exacerbated allergic reactions, for example, in hypersensitivity to some medicines like penicillin and sulfas, may cause anaphylactic shock, a severe clinical condition that sometimes leads to death.

The body has many defense mechanisms against foreign pathogenic agents. These mechanisms are divided into two groups: the specific mechanisms and the unspecific mechanisms. The specific mechanisms are part of the immune system and comprehend the humoral immune response and the cellular immune response that respectively produce antibodies and defense cells against specific antigens. The unspecific mechanisms fight in a general manner any type of antigen (they do not have specificity) and in them a series of defense means are included, like the skin barrier against foreign agents, the mucous and ciliated epithelium of the airway, inflammation (the inflammatory response) and the action of unspecific proteins and defense cells (e.g., interferons and macrophages).

Vaccines can be constituted of dead agents of disease, of inactivated agents of disease, of inactivated toxins or of fragments of the infectious agent.

Examples of some vaccines and their type of antigenic agents are: BCG, inactivated tuberculosis bacilli; antitetanic vaccine, inactivated toxin; antidiphtheric, inactivated toxin; antipolio Salk, dead poliovirus; antipolio Sabin, attenuated (inactivated) poliovirus.

The main leukocytes that generally multiply and participate in the defense against worm infections are the eosinophils. In this type of inflammation the blood level of these cells are increased, a clinical condition known as eosinophilia.

Eosinophils are also increased in allergic conditions.

Vaccines are not used in the treatment of infections because they depend on the primary immune response that takes about a week to occur and is not so intense and effective. Antivenom serums however are inoculated into the circulation and used as an immediate treatment because they are made of a great amount of immunoglobulin (antibodies) which is potent against their respective specific venom.

The DNA vaccine, or DNA vaccination, is a vaccination technology based on genetic engineering. In DNA vaccination a recombinant plasmid (vector) containing the gene of a specific antigen that is part of a given pathogenic agent is inserted into cells of the individual to be immunized. These cells then begin to produce the antigen that triggers the primary immune response and theoretically the individual becomes immunized against that antigen.

Natural active immunization is that in which a previous natural infection induces the primary immune response, specific memory cells are produced and the individual becomes immune to new infections with the antigen. This is what happens in diseases that affect people only once in life, like mumps and chickenpox.

Artificial active immunization is that in which the primary immune response is caused by the inoculation into an individual of specially prepared antigens. This is the case with vaccines.

Diseases caused by the action of the own immune system of the individual are called autoimmune diseases.

The autoimmune diseases appear when the immune system makes antibodies or defense cells that attack cells, tissues and organs of its own body. The attacked cells or tissues are wrongly recognized as antigens by the immune system. Rheumatoid arthritis, lupus, scleroderma, vitiligo, pemphigus, type I diabetes mellitus, Crohn's disease (chronic inflammation of the gut), myasthenia gravis, Graves disease, Hashimoto's disease, etc., are all examples of autoimmune diseases.

The lymphocytes that participate in the cellular immune response are the T lymphocytes. T lymphocytes differentiate into three main types: cytotoxic T lymphocytes (cytotoxic T cell), helper T lymphocytes (helper cell) and suppressor T lymphocytes. The cytotoxic cells are the effectors of the system, i.e., they directly attack other cells recognized as foreign (for example, fungi cells, cells infected by virus, neoplastic cells, graft cells, etc.). The helper cells and the suppressor T lymphocytes act as regulators of the system releasing substances that respectively stimulate and inhibit the immune action of T and B lymphocytes. After the primary immune response memory T lymphocytes also remain in the circulation to provide faster and more effective reaction in case of future infections.

Active immunization is that in which an antigen penetrates the body triggering the primary immune response and the production of memory lymphocytes and antibodies that provide faster and more effective immune defense in future infections by the same antigen. Passive immunization is that in which immunoglobulins against an antigen are inoculated in the body to provide protection in case the body becomes infected by the antigen.

Active immunization tends to be longer lasting than passive immunization since in the active type as well as antibodies, specific memory lymphocytes remain in the circulation. In the passive immunization the duration of the protection is that of the duration of the antibodies in the circulation.

Besides being nutritionally important, maternal milk participates in the defense of the baby against infectious agents. Soon after delivery the mother produces a more fluid milk called colostrum that is rich in immunoglobulins (antibodies). These antibodies are not absorbed by the baby’s circulation but they cover the internal surface of the baby’s bowels thus attacking possible antigens and making more difficult the proliferation of pathogenic bacteria within the organ.

The antigen-presenting cells of the immune system, also known as APC cells, are cells that do phagocytosis and digestion of foreign (to the body) microorganisms and later expose antigens derived from these microorganisms in the outer side of their plasma membrane. These processed antigens are then recognized by lymphocytes that activate the immune response. Several types of cells, like the macrophages, can act as antigen-presenting cells.

The competent authority to amend the Fundamental Rights is the Union Parliament

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The cells that produce antibodies, i.e., the cells of the humoral immune system, are the B lymphocytes (B cells).

The Prime Minister of India who did not face the Union Parliament was Charan Singh

(b) He will have the right to vote in Parliament

The monthly salary of the President of India is now  Rs 150000

(e) Right to negotiate

Not more than 6 months shall elapse between the date on which a House is prorogued and the commencement of its next session.