What is Immunology?

Immunology is the division of science involved with the immune reactions occurring in living organisms. The organisms are accustomed to evolving internal defense mechanisms to evade the invasion of microbial pathogens. Diverse cells are connected with stimulating the immune responses, which produce inhospitable conditions to the microbes prompting their lysis and thus inhibits the multiplication of the pathogens. The immune system can distinguish the pathogens through the aid of cellular intercommunication and launch responses to destroy them.

Classification of Immunology

Immunology is grouped into different types based on its characteristics. The classification includes clinical immunology, classical immunology, and developmental immunology. Clinical immunology is concerned with the diseases related to the immune system, which can result from diverse features encompassing the malignant development of cells, or inactivation of the immune cells in response to an antigen. It is also associated with various disorders affected at other times of the body caused due to the failure of the immune system. The classification of immune disorders includes immune deficiency and autoimmunity.

What Arena Immune Deficiency and Autoimmunity?

The immune deficiency is the lack of proper response of the immune system and autoimmunity is characterized by the development of immunity against the body tissues that causes the degeneration of the respective tissues and the cells. An example of an immunodeficiency disorder is the granulomatous disease and that of autoimmune disorder includes Hashimoto’s disease and rheumatoid arthritis. The hypersensitivity responses are also considered as the defects of the immune system, where a patient develops an excessive immune response against a particular antigen or allergen, which results in the development of disorders such as allergy and asthma. 

Types of Immunity

Classical immunology deals with the study of interactions between immunity, pathogens, and the body system. It is concerned with various immune cells and other components that stabilize the action of the immune system. Thus, classical immunology encompasses the innate immune system and the adaptive immune system. The innate immune system is present in the body by birth and the adaptive immune system is developed in the body during the lifetime. The innate immune system includes the physiological barriers and cellular components that function broadly against pathogens. Adaptive immunity is found to be more specific in action against pathogens. It possesses the capacity to mediate non-self and self-recognition. The antigens are concerned with eliciting an immune response in the body. The lymphocytes are the type of cells associated with identifying the antigens. After identification, antibodies are released and act against specific antigens by neutralizing the adverse effects of the antigens. The antibodies signal the phagocytes and thus aids in the process of phagocytosis of the antigens. These antigens are mostly found on the external surface of the microbes. The antibodies have active sites complementary to these antigens that facilitate antigen-antibody binding.

Developmental immunology includes the variations in immune responses of the body based on age and other factors including the type of antigen and maternal factors. The neonates are identified to be in the neutral stage as they have suppressed adaptive and innate immunological activity. The opsonic activity is found to be restricted in the neonate and they are prone to infections caused by microbes including Pseudomonasand Staphylococcus. The monocytes have a lower level of functionality and the cells generate lesser amounts of cytokines including IL (interleukin)-12, IL-4, IL-2, and IL-5. The Bcells are found to be developed during the primary stages of gestation and are not completely operational. The immunoglobulin G (IgG) is conveyed from the mother to the offspring along with some levels of IgA. These antibodies ensure the protection of the offspring for about 18 months.

Cells of the Immune System

The immune system functions in synchronization with numerous cells found in the body. The white blood cells are mainly concerned with triggering the immune response in the body. There are diverse white blood cells and each of them is assigned particular role in the immune system. The distinctive varieties of white blood cells comprise neutrophils, basophils, eosinophils, macrophages, B lymphocytes, and T lymphocytes. The cells including the eosinophils, basophils, and neutrophils are classified under granulocytes and the macrophages are classified under the monocytes. The neutrophils are the primary line of cellular defense. They possess granules consisting of enzymes including the catalases and nucleosidases. The eosinophils are active against the parasites and the basophils mediate the allergic responses of the body. The monocytes are phagocytic and undergo development to form macrophages. The lymphocytes include the B lymphocyte and T lymphocytes, where T lymphocytes mediate cellular immunity and the B lymphocyte mediate the humoral immunity.

Primary and Secondary Immune Responses

The immune responses are grouped into primary and secondary immune responses. The primary responses are triggered with the entry of the pathogen. It is less specific and functions broadly to avoid the invasion of all types of foreign pathogens. This mode of response initiates the allergic responses characterized by inflammation and reddening of the affected site. This response elevates the rate of blood flow to the particular site and neutralizes the invasion of the pathogens. The secondary immune response takes place after the primary invasion of the pathogens. The immunogenic information is collected by the B memory cell during the primary invasion which further mediates the formation of specific antibodies against the respective antigen. These antibodies are discharged when the same antigen invades the body a second time. Upon second exposure, a more powerful immune response is generated which completely destabilizes the antigen. The secondary immune response aids in the development of immunity against a particular pathogen. This type of immunity is mainly developed against viral infections.

Content and Applications

This topic is significant in the professional exams for both undergraduate and graduate courses, especially for

• Bachelors in Zoology
• Bachelors in Microbiology
• Bachelor of Medicine
• Bachelor of Surgery and other related fields

Related Concepts

• Cell Biology
• Microbiology
• Molecular Biology