Immunity: defense and attack

Inflammation is tissue response to infection or damage.

The inflammatory process involves plasma proteins, i.e. the complement, and cytokines. The complement is a number of plasma proteins entering a series of cascade chemical reactions in response to infection. This is a multistage signal system of a kind that marks foreign microorganisms, and attracts special pathogen killer cells to the infection site.

In response to alarm signal, cell-mediated immune response is triggered off. Two types of blood cells, i.e. phagocytes and NK-cells (natural killer cells), are engaged in non-specific immune response.

Phagocytes are large leukocytes that consume and literally digest microorganisms and other foreign particles. This process is called phagocytosis. Phagocytes are most sensitive to complement- or antibody-marked microorganisms (these particles are already part of adaptive, or specific, immune response). Besides the cells that attack the invaders in response to alarm, specific leukocytes, or NK-cells, are regularly present in the blood flow. They target malignant and virus-infected cells. Innate immunity quickly activates at early infection stages. Its protective mechanisms may contain pathogen distribution in the body, but it has limited capabilities for removing foreign particles, and these capabilities remain the same in case of reinfection with the same pathogen. Therefore, the third protection line is usually required to fight infection, i.e. the adaptive immune system (acquired immunity).

Adaptive (acquired) immunity develops after the first encounter with a foreign agent. Its main properties are specificity, and immune memory.

Specific immunity mainly relies on lymphocytes that are specialized leukocytes residing in the lymphatic system. Lymphocytes are characterized by a very long lifecycle — several years to decades. There are three lymphocyte types: B-cells, T-cells, and natural killers.

For adaptive immunity development, a specific target is required, i.e. an antigen. An antigen is a substance (usually a large molecule) that activates immune response. A microorganism generally has many antigens, e.g., surface structures, such as cell wall components, capsular polysaccharides, flagella etc., or extracellular proteins, such as toxins or enzymes produced by the microorganism.

First, B-cells produce proteins that will react with the antigen thus making it harmless. These proteins are called antibodies also known as immunoglobulins (Ig). Antibodies are highly specific, and are capable of binding only to an antigen of the same structure as the one that has initially triggered off their formation.

Then the acquired immunity starts acting simultaneously in two directions: humoral immune response targets antigens present in plasma, and cell-mediated immune response targets pathogens present inside the cells.

In the humoral immune response process, an accelerated fission of specific antigen- activated B-cells starts that results in the formation of a large number of identical cell clones, each of which can fight this antigen. B-cell antibodies are attract phagocytes killing and digesting the target antigen.

The cell-mediated immunity uses “special task force”, i.e. T-helpers and cytotoxic T-cells directly targeting and killing infected cells.

After the infection is overcome, antigen-activated B- and T-cells turn dormant, and become memory lymphocytes specific to a given antigen or pathogen. In reinfection by the same or very similar (antigenically similar) microorganism, they provide for a fast and powerful immune response. High concentrations of the antibodies required are reached 1-2 days after infection.

Thus, acquired immunity has three main features:

• Specificity: every antibody or activated T-cell reacts only with a specific antigen that has caused its formation. At the same time, they do not react with other antigens, and protect the body only from diseases characterized by the presence of a given antigen.

• Memory: after a specific antibody or T-cell forms in the adaptive immune response process, antibody production, or T-cell activation proceeds faster, and in large quantities. This feature is the basis of the effect of many vaccines.

• Tolerance to own tissues: normal adaptive immune response mechanisms are capable of distinguishing between the body’s own and foreign structures.

There are a lot of immunity compromising factors in modern life, such as adverse environmental effects, stresses, heavy physical activities or mental workload, excessive fatigue, and not getting enough sleep, improper nutrition and, as a result, vitamin and mineral deficiencies, protein-energy malnutrition, bad health habits (alcohol abuse and smoking), physical inactivity, chronic diseases, and non-rational use of antibiotics.

The compromised immune system causes exacerbation of chronic infections, or, on the contrary, promotes transition of acute infectious diseases into a chronic form, which further overstrains immunity, and may ultimately lead to the formation of secondary immunodeficiency (SID).

The signs of the compromised immune system are as follows:

• exacerbation of chronic infections;

• transition of acute diseases into a protracted, and then into a chronic form. Normally, acute infections will resolve as full recovery within 2-4 weeks;

• growth of opportunistic infection incidence rate (mucosal candidiasis, herpetic infection);

• allergic and autoimmune diseases;

• chronic fatigue syndrome.

The core sign of secondary immunodeficiency (SID) is an increased infectious disease morbidity rate.

The SID risk group includes:

• children, and the elderly aged 60+;

• subjects living or working in adverse environmental conditions, and permanently exposed to harmful factors (radiation, chemical pollution etc.);

• subjects employed in stressful jobs (pilots, submariners), or those exposed to ultra-intense physical activities, and extreme temperatures;

• patients after devastating infections, and severe injuries.

SID syndrome signs:

• frequent exacerbations of chronic inflammatory diseases;

• frequent ARVI (more than 5-6 times a year);

• frequent exacerbations of herpetic infection;

• standing subfebrile body temperature (~37.5 °С);

• enlarged lymph nodes;

• inefficacious standard treatment assigned for a given infectious disease.

Immunocorrection is widely used in medical practice to remove immunodeficiency and maintain a normal immunity level in stressful environments. It is performed using special-purpose medicinal products, i.e. immunomodulators.

If immune protection functions normally, the body wins over acute infections. Chronic inflammation is always caused by an immune system failure, incapacity to defeat the infectious agent, and complete the pathological process. In such cases, it is impossible to achieve satisfactory treatment results without immune system activation.

A similar situation may be observed in treatment of chronic ulcers, and non-healing wounds. Their presence signals that, for some reason, the immune system has overcome the infection, but cannot repair damaged tissues, or form an adhesion instead of the damaged tissue. In other words, the immune process fails at the final stage. Consequently, for successful treatment, it is also necessary to activate the repair mechanisms of the immune system.

Immunomodulating therapy is a therapeutic action aimed at mitigating an adverse immune reaction (including allergic, and autoimmune) together with strengthening the anti-infective immunity function. Immunomodulators are pharmaceuticals that, when used at therapeutic doses, restore the damaged anti-infective capability of the body.

Polyoxidonium is a true immunomodulator that activates all links of human immune system providing for an efficient and adequate immune response to diseases of any origin (bacterial, viral, and fungal).