Immunology Lecture 1 PDF

Asst. Prof. Sheila M. Nuraddin Clinical Analysis Department College of Pharmacy Hawler Medical University Lec:1 Outlines Imunology Historical background of Immunology Terminology Immunology: is defined as the science that study the molecules, cells, organs, and systems responsible for the recognitio...

Asst. Prof. Sheila M. Nuraddin Clinical Analysis Department College of Pharmacy Hawler Medical University Lec:1 Outlines Imunology Historical background of Immunology Terminology Immunology: is defined as the science that study the molecules, cells, organs, and systems responsible for the recognition and disposal of foreign material. Historical Background of Immunology Immunology began as a branch of microbiology. The study of infectious disease and the body’s response to them has a major role for the development of immunology. More over, the concept of germ theory of disease has contributed to the field of immunology. It was Edward Jenner who first studied the response of the body to foreign substances. He observed that dairymaids who had naturally contracted a mild infection called cowpox seemed to be protected against smallpox, a horribly disfiguring disease and a major killer. In 1796, Jenner inoculated an eight year-old boy with fluid from cowpox blisters on the hand of a dairymaid. The boy contracted cowpox. Then two months later Jenner inoculate him with fluid from a small pox blister, the boy only developed a small sore at the site of inoculation. His exposure to the mild disease cowpox had made him immune to the small pox infection. These were some of the vital events occurred in the history of immunology following Jenner’s achievement. Terminology Immunity refers to protection against infection. The immune system is the collection of cells, tissues and molecules that functions to defend us against infectious microbes. The coordinated reaction of the immune system against infections (and other foreign substances) is known as (The immune response). Immunoglobulins: class of proteins that make up antibodies Antibody A protein (immunoglobulin) that recognizes a particular antigen and binds specifically to it, is called an ‘antibody Antibodies are produced by B cells. * Classification of Antibodies (Immunoglobulins) * Immunoglobulin M (IgM) * Immunoglobulin G (IgG) * Immunoglobulin A (IgA) * Immunoglobulin D (IgD) * Immunoglobulin E (IgE) Antigen Any substance (usually foreign) that binds specifically to an antibody, or a T cell receptor, is referred to as an ‘antigen’. A substance capable of inducing a specific immune response is called an antigen. Antigens are macromolecules that elicit an immune response in the body. The most common antigens are proteins and polysaccharides. Immunogen: antigen that stimulates an immune response Antigenic determinants: The chemical groups on the antigen molecules that determine their immunogenicity are called antigenic determinants, also known as epitopes. Hapten: antigen that is too small to set off an immune response, viruses are common hapten, when they are small, they soon replicate and grow larger, thus setting off an immune response. Cytokines : secreted proteins with low-molecular-weight, made in response to pathogens and other antigens that regulate and mediate inflammatory and immune responses. Cytokines bind to specific receptors on target cells. Originally were called lymphokines because they were initially thought to be produced only by lymphocytes, Then monokines because they were secreted by monocytes and macrophages, Then interleukin because they are produced by some leukocytes and affect other leukocytes. The term “cytokine” is now used more widely and covers all of the above. Interleukins (IL)( secreted signaling molecules) are a type of cytokine first thought to be expressed by leukocytes alone but have later been found to be produced by many other body cells. They play essential roles in the activation and differentiation of immune cells, as well as proliferation, maturation, migration, and adhesion. They also have pro-inflammatory and anti-inflammatory properties. Complement System The complement system is a biochemical cascade of the immune system that helps clear pathogens from an organism, and promote healing. It is derived from many small plasma proteins that work together to form the primary end result of cytolysis by disrupting the target cell’s plasma membrane The Immune System In basic terms, the immune system has two lines of defense: innate immunity and adaptive immunity. Innate immunity is the first immunological, nonspecific (antigen-independent) mechanism for fighting against an intruding pathogen. It is a rapid immune response, occurring within minutes or hours after aggression, that has no immunologic memory. Adaptive immunity, on the other hand, is antigendependent and antigen-specific; it has the capacity for memory, which enables the host to mount a more rapid and efficient immune response upon subsequent exposure to the antigen. There is a great deal of synergy between the adaptive immune system and its innate one. Any defects in either system can provoke illness or disease, such as autoimmune diseases, immunodeficiency disorders and hypersensitivity reactions. Innate Immunity Acquired immunity Depends of pre-formed cells and molecules Depends on clonal selection, i.e. growth of T/B cells, release of antibodies selected for antigen specifity Fast (starts in mins/hrs) Slow (starts in days) Limited specifity- pathogen associated, i.e. recognition of danger signals Highly specific to foreign proteins, i.e. antigens Cells involved: - Neutrophils (PMN) - Macrophages - Natural killer (NK) cells Cells involved : - T lymphocytes - B lymphocytes - Dendritic cells - Eosinophils - Basophils/mast cells Soluble factors involved - Acute-phase proteins - Cytokines - Complement Soluble factors involved - Antibodies