Immune Response And Its Components

The immune system is prepared for any attack from outside. Each component has its role depending on the pathogen that intervenes.
Immune response and its components

Our species is constantly threatened by a large number of pathogens. Thus, to defend itself the body gives an immune response  which allows it to strengthen the system. In this way, the immune system’s job is to ensure the integrity of the body. In addition, it is in charge of detecting cellular degeneration and preventing the development of cancer.

While it’s not easy to explain, the various components of the immune system are organized to protect us from any external attack. The problem, however, is that there are certain agents that can compromise or overcome the defenses of this system and therefore its immune response .

Structural components of the immune response

The structural components of the immune response fall into two types: primary and secondary. Primaries produce and differentiate lymphocytes, while secondary detect and analyze antigens.

Lymphocyte cell

Primary structural component

The thyme

The thymus is a primary and specialized lymphoid glandular organ that is part of the immune system. T cells (lymphocytes) mature within this gland. T cells are indispensable for the adaptive immune system and through it the body adapts specifically to external invaders.

The thymus is located in two lobes behind the breastbone. Thus, it is an organ sensitive to glucocorticoids and its function is to educate the T lymphocytes (make them mature).

The bone marrow

It is a tissue found inside long bones such as the breastbone, ribs, vertebrae, skull bones, pelvis and even the shoulder girdle. It is formed by islets of hematopoietic cells, thus, this organ is in charge of the differentiation of immune cells, especially B lymphocytes.

Secondary structural components

The spleen

The spleen is an organ that is part of the lymphatic system  and is located in the upper left part of the abdomen. He is in charge of:

  • Filter the blood.
  • Withdraw old erythrocytes.
  • Capturing blood antigens.

The lymphatic nodules

Lymphatic ganglia (or lymphatic nodules) are organs of the immune system. They have an ovoid shape and are distributed throughout the body and joined by lymphatic vessels. They are responsible for filtering external particles and are therefore of great importance in the proper functioning of the immune response.

 The tonsils

These are two organs that deal with the transaction of the nasal and oral cavities. Their growth depends on age and reaches its maximum in childhood, decreasing thereafter. In case of infection, however, they enlarge.

Peyer’s plaques

They are found in the intestinal wall. These are accumulations of lymphatic tissue that internally cover the walls of the small intestine. They are cells that are sensitized and specialized in identifying antigens associated with food.

Non-lymphatic organs

In addition to those already mentioned, other non-lymphatic components, antibodies or immunoglobulins, are part of the structural components of the immune response. These are found:

  • In the secretions of the gastrointestinal and respiratory systems.
  • In the salivary glands.
  • In the tear duct
  • In the mammary glands.
  • In the mucous membranes.

Cellular components of the immune response

The cellular components of the immune response are 54% formed from plasma. Plasma is the part of the acellular blood. It is obtained by leaving the blood devoid of cells such as red blood cells and white blood cells. In addition, there are plasma cells which occupy 46% of the immune response. These are the erythrocytes and leukocytes.

Among the leukocytes we can find:

  • Granulocytes. These are classified into:
    • Neutrophils: They act in inflammation. They are more common in human blood.
    • Eosinophils: They act against parasites.
    • Basophils: They are activated against allergy.
  • Monocytes or macrophages.
  • Lymphocytes. In this group we can distinguish B lymphocytes and T lymphocytes. In addition, NK lymphocytes are activated when a specific response is given.


B lymphocytes and T lymphocytes intercede in the specific immune response. NK lymphocytes ( Natral Killer  in English) are activated instead with the non-specific response. Below we will explain what each type of lymphocyte does.

T lymphocytes

The pioneers of T lymphocytes are formed in the bone marrow, then migrate to the thymus and are “educated” there. They are divided into various types:

  • T helper lymphocytes (helpers). They are the ones who initiate the immune response. In addition, they increase the effectiveness of macrophage phagocytosis. They are also in charge of the proliferation and differentiation of T and B lymphocytes.
  • Cytoxic T lymphocytes. They deal with destroying virus-infected cells and cancer cells.
  • Suppressor T lymphocytes. They conclude the immune response.
Lymphocytes under the microscope

B lymphocytes

The function of these lymphocytes is the production of antibodies (immunoglobulins). In turn, immunoglobulins are glycoproteins that differ in their structure and function into IgM, IgD, IgG, IgA and IgE. Thus, they have the following functions:

  • IgM. They take charge of the primary immune response.
  • IgD. They are found in the surface of B cells.
  • IgG. Secondary immune response. They are able to cross the placenta.
  • IgA. They are found in the mucous membrane and saliva. They can also be present in breast milk.
  • IgE. They are activated when an allergic reaction is in progress.

The role of immunoglobulins is concentrated in:

  • Avoid binding of antigens with cells.
  • Coat and glutinate antigens.
  • Promote phagocytosis by macrophages and neutrophils.
  • Initiate inflammation and mobilization of macrophages.
  • Collaborate with the complement system which destroys the antigen.

Based on the identified threat, certain cells are activated and, therefore, a specific part of the immune system. This is how the body protects us from the various antigens that invade us every day.

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