Abstract:
Our understanding of the immune system and how it defends the body against illness is
constantly expanding. An in-depth analysis of every facet of immunology is outside the purview of this
article due to the subject's complexity. Instead, this article aims to give medical students, residents,
primary care physicians, and other healthcare workers a fundamental overview of the immune system's
major parts, functions, and involvement in both health and disease. Additionally, this article will
provide background information on the immunopathological conditions covered in the rest of this
supplement. Innate immunity and adaptive immunity are the immune system's two main lines of
protection, which go beyond physical and chemical barriers to infections. The initial immune defense
against an invasive infection is innate immunity. It is a quick immunological reaction without
immunologic memory that starts minutes or hours after violence. Conversely, adaptive immunity is
antigen-specific and antigen-dependent; it possesses memory, which allows the host to develop a
quicker and more effective immune response when the antigen is encountered again. The innate and
adaptive immune systems work in tandem very well, and deficiencies in either system can lead to
diseases like immunodeficiency disorders, autoimmune diseases, hypersensitivity reactions, and
inappropriate inflammation. This article provides a practical overview of innate and adaptive immunity,
and describes how these host defense mechanisms are involved in both heath and illness.
