Immunity definition in immunology
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Immunity Definition in Immunology: Key Concepts
Immunity as Protection Against Disease
In immunology, immunity is defined as the state of protection against foreign pathogens or substances, also known as antigens. The immune system evolved to defend the body from infectious agents such as viruses, bacteria, fungi, protozoa, worms, and toxins, keeping the burden of disease at bay Kiboneka2021Khan2019Singh2021. Immunity can be present at birth (innate) or acquired during life (adaptive) .
Innate and Adaptive Immunity: The Two Main Types
Immunity is broadly divided into two main types: innate (natural) immunity and adaptive (acquired) immunity. Innate immunity provides the first, rapid line of defense and is not specific to particular pathogens. It includes physical barriers, chemical barriers, and immune cells like macrophages, neutrophils, and dendritic cells that recognize common patterns on pathogens Kiboneka2021Marshall2018Pradeu2024. Adaptive immunity, on the other hand, is slower to develop but is highly specific to particular antigens and has the capacity for immunological memory, allowing for a faster and stronger response upon re-exposure to the same pathogen Kiboneka2021Marshall2018Alam2007.
Mechanisms and Components of the Immune System
The immune system is made up of various cells and molecules that work together to protect the body. All blood cells, including those of the immune system, originate from hematopoietic stem cells in the bone marrow. The adaptive immune system includes lymphocytes (such as B cells and T cells), antigen-presenting cells, and effector cells that eliminate microbes . The innate immune system relies on pattern recognition receptors (PRRs), such as Toll-like receptors, to detect pathogens Kiboneka2021Pradeu2024.
Immunological Memory and Trained Immunity
Traditionally, immunological memory—the ability to respond more effectively to previously encountered pathogens—was thought to be exclusive to adaptive immunity. However, recent research has shown that innate immune cells can also develop a form of memory, known as "trained immunity." This involves long-term changes in innate immune cells, such as monocytes and macrophages, allowing them to respond more robustly to future infections. Trained immunity is driven by epigenetic reprogramming and can be beneficial in fighting infections, though it may also contribute to inflammatory diseases if not properly regulated Ochando2022Netea2016.
Immunization and Disease Prevention
Immunization is the process of making a person immune or resistant to an infectious disease, typically through vaccination. Vaccines stimulate the immune system to develop protection without causing the disease itself, leveraging both innate and adaptive immune responses .
Conclusion
In summary, immunity in immunology refers to the body's ability to protect itself from infectious diseases and harmful substances. This protection is achieved through a complex system involving both innate and adaptive mechanisms, specialized cells, and molecular pathways. The discovery of trained immunity has expanded our understanding of how the immune system can remember and respond to threats, highlighting the dynamic and adaptive nature of immune protection Kiboneka2021Khan2019Marshall2018+3 MORE.
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An introduction to immunology and immunopathology
Innate and adaptive immunity are fundamental lines of defense in the immune system, and defects in either system can lead to illness or disease.
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