Structure and Function of the Immune System
All defense reactions of the body unfold on the basis of the lymphatic system, which serves as the morphological foundation of immunity. The effector elements of the system are divided into two categories:
- Cellular factors: specialized T and B lymphocytes, as well as phagocytes.
- Humoral factors: antibodies, complement system proteins, interferons, and other soluble substances.
The main principle of immunity is the close cooperative interaction of all these elements. The core mechanism of action always consists of two stages:
- Fine discrimination — infallible recognition of "self" and "non-self".
- Physical destruction, neutralization, or degradation of the detected foreign agent.
Classification of Defense Objects (Antigens)
The immune system reacts to any substances carrying signs of genetic foreignness. In immunology, they are called antigens (from Greek anti — against, genes — birth/origin). All antigens are divided into two large groups depending on their origin within the body.
Exogenous antigens (entering from the outside):
- Various microorganisms (bacteria, viruses, and other pathogens).
- Antigens of plant and animal origin.
- Chemically synthesized substances.
Endogenous antigens (generated inside the body):
- Autoantigens (own tissues that have become targets).
- Specific tumor antigens.
- Products of cellular and molecular mutations that the immune system must recognize and destroy in a timely manner.
Clinical Significance and Current Trends
Modern immunology has long gone beyond the scope of combating microbes alone. Today, its achievements are critical for a wide range of medical disciplines. It addresses problems in infectious diseases, allergology, and plays a key role in transplantology (organ and tissue transplantation) and oncology (diagnosis and treatment of tumors).
The most relevant and complex areas of clinical immunology include:
- Immunological conflicts: study and prevention of incompatibility between the mother's body and the fetus during pregnancy.
- Immunodeficiencies: development of prevention and treatment methods for both congenital and acquired forms of immune insufficiency.
- Genetic technologies: introduction of gene therapy and gene prevention methods for treating severe diseases associated with immune system damage.
Briefly: answers to topical questions
What classes of immunoglobulins exist in the human body?
In the human body, immunoglobulin molecules are divided into five classes (isotypes).
- Immunoglobulin G (IgG) — includes isotypes IgG1, IgG2, IgG3, and IgG4; detected in secondary infection, while stably low titers indicate a past infection.
- Immunoglobulin M (IgM) — acts as a marker of recent infection and acute infection.
- Immunoglobulin A (IgA) — includes isotypes IgA1 and IgA2; detected in chronic infection and carrier state.
- Immunoglobulin E (IgE) — a class of antibodies whose synthesis is induced by the cytokine IL-4.
- Immunoglobulin D (IgD) — the fifth class in the general classification of isotypes.
To remember the main mechanism of the immune system, use the simple rule "RD": R — Recognition ("self/non-self"), D — Destruction (neutralization of the foreign agent).
Class and exam questions
What belongs to the humoral factors of immunity?
Humoral factors include protective substances dissolved in the body's internal fluids: antibodies, the complement system, and interferons.
Where do endogenous antigens come from?
Endogenous antigens are formed inside the body itself as a result of cellular or molecular mutations, the transformation of normal cells into tumor cells, and the formation of autoantigens.
What is an immunological conflict?
This is an incompatibility reaction that can occur, for example, between the mother's immune system and the genetically distinct organism of the fetus.
What else to study on this topic
- Cooperative Interaction of T and B Lymphocytes
- Functions of Antibodies and the Complement System
- Mechanisms of Tumor Antigen Recognition
- Congenital and Acquired Immunodeficiencies
- Principles of Gene Therapy in Clinical Immunology
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