Downloaded 152 times
More Related Content
Similar to Cells of the immune system
More from Praveen Garg
Cells of the immune system
- 1. Mrs. Praveen Garg VITSCollege, Satna
- 2. Introduction Our immunesystem is essential for our survival. Without an immune system, our bodies can be attacked by bacteria, viruses, parasites, and more. The immune system is spread throughout the body and involves many types of cells, organs, proteins, and tissues. It can recognize our tissue from foreign tissue — self from non-self. Dead and faulty cells are also recognized and cleared away by the immune system. If the immune system encounters a pathogen, such as bacterium, virus, or parasite, it is called immune response.
- 3. Immune cells Immunecells develop from stem cells in the bone marrow and become different types of white blood cells. Stem cells can differentiate into other cell types, they are self renewing and maintain their population by cell division. These include neutrophils, eosinophils, basophils, mast cells, monocytes, macrophages, dendritic cells, natural killer cells, and lymphocytes (B cells and T cells). The cells of the immune system can be categorized as lymphocytes (T-cells, B-cells and NK cells), neutrophils, and monocytes/macrophages. These are all types of white blood cells. The major proteins of the immune system are signaling proteins (often called cytokines), antibodies, and complement proteins.
- 4.
- 5. Cells of theImmune system Lymphocytes are the central cells of the immune system, responsible for adaptive immunity and immunological diversities and self/non self response. The other type of white blood cells play important role in engulfing and destroying microorganisms, presenting antigen and secreting cytokines.
- 6. Types of Immunity Innate immunity has anatomical and physiological barriers, cellular internalization mechanisms, and inflammatory responses that are rapidly induced by the presence of antigen. Innate immune mechanisms inhibit pathogen entry, prevent the establishment of infection, and clear both host and microbial debris. Adaptive immunity is an immunity that occurs after exposure to an antigen either from a pathogen or a vaccination. This part of the immune system is activated when the innate immune response is insufficient to control an infection. The adaptive immune system works to protect and heal the body when the innate immune system fails.
- 9. Lymphoid Cells Lymphocytesconstitute 20%-40% of the white blood cells and 99% of the cells in the lymph. These lymphocyte circulate in the blood and lymph and are capable of migrating into tissue space and lymphoid organs. The lymphocytes can be divided into three population- B cells, T cells and natural killer (NK) cells on the basis of function and cell membrane component. NK cells are large, granular lymphocyte and act as phagocytic cells. B and T lymphocytes cells are small, motile, non phagocytic cells. Small lymphocyte enlarge into blast cells, called lymphoblasts. These lymphocytes interact with antigen and response against them.
- 10. B lymphocytes (BCell) In mammals, B cells derived and mature in the bone marrow or in the lymph node, which is at the core of most bones. In birds, B cells mature in the bursa of Fabricius, a lymphoid organ where they were first discovered by Chang and Glick. They function in the humoral immunity component of the adaptive immune system. B cells produce antibody molecules, however, these antibodies are membrane bound, not secreted. When a naïve or memory B cell is activated by antigen, it proliferates and differentiates into an antibody-secreting effector cell, known as a plasmablast or plasma cell. Additionally, B cells present antigens, they are also classified as antigen-presenting cells (APCs) and secrete cytokines.
- 12. B cellhas the binding site for antigen and various molecule expressed on the surface of b cells: B220: It is form of CD45, frequently used as a marker for B Cells. Class II MHC: It permit the B cell to function as antigen presenting cell (APC). FcγRII (CD32) is a receptor for IgG antibody. B7-1 & B7-2 are molecule that interact with CD28 and CTLA- 4,important regulatory molecule on the surface of different types of T cell. CD40 is a molecule that interact with CD40 ligand on the surface of helper T cells.
- 13. Types of BLymphocytes B lymphocytes are two types. Plasma Cell: Once activated, B lymphocytes can differentiate into plasma cells. Memory B Lymphocyte: Some B lymphocytes will differentiate into memory B cells, which are long- lived cells that remain within the body and allow a more rapid response to future infections.
- 14. T lymphocyte Tcells (also called T lymphocytes) are one of the major components of the adaptive immune system. Their roles include directly killing infected host cells, activating other immune cells, producing cytokines and regulating the immune response. T cells originate in the bone marrow and mature in the thymus. In the thymus, T cells multiply and differentiate into helper T cell or regulatory cell and or cytotoxic T cells or become memory T cells. They are then sent to peripheral tissues or circulate in the blood or lymphatic system. Once stimulated by the appropriate antigen, helper T cells secrete chemical messengers called cytokines, which stimulate the differentiation of B cells into plasma cells (antibody-producing cells). Regulatory T cells act to control immune reactions, hence their name. Cytotoxic T cells, which are activated by various cytokines, bind to and kill infected cells and cancer cells.
- 16. Natural Killer cells Natural Killer (NK) Cells are lymphocytes in the same family as T and B cells, coming from a common progenitor. NK cells secrete cytokines such as IFNγ and TNFα, which act on other immune cells like Macrophage and Dendritic cells to enhance the immune response. NK cells are known to differentiate and mature in the bone marrow, lymph nodes, spleen, tonsils, and thymus, where they then enter into the circulation. NK cells are activated in response to interferons or macrophage-derived cytokines. They serve to contain viral infections while the adaptive immune response generates antigen-specific cytotoxic T cells that can clear the infection.
- 17. Macrophages Macrophages arespecialised cells involved in the detection, phagocytosis and destruction of bacteria and other harmful organisms. In addition, they can also present antigens to T cells and initiate inflammation by releasing molecules (known as cytokines) that activate other cells. Kupffer cells: Liver Histocytes: Connective tissue Mesanglial cells: Kidney Microglia: Central nervous system Alveolar macrophage: Lung alveoli Osteoclasts: In bones Macrophages, are constituents of the reticuloendothelial system and are found in the lymph nodes, in the intestinal tract, and as free-wandering and fixed cells. Activated macrophages also express high levels of Class II MHC molecule and involve in phagocytosis.
- 18. Macrophages Phagocytois & Processingof antigen
- 19. Granulocyte cells Thegranulocytes are classified as neutrophiles, eosinophils, and basophils on the basis of cellular morphology and cytoplasmic staining characters. Neutrophills Basophills Eosinphills
- 20. Neutrophiles Neutrophils (alsoknown as neutrocytes or heterophils) are the most abundant type of granulocytes and make up 40% to 70% of all white blood cells in humans. They form an essential part of the innate immune system. It has a multilobed nucleus and granulated cytoplasm that stain with both acidic and basic dye. It is also known as polymorphonuclear leucocyte. Neutrophils are the most abundant white blood cells in humans, approximately 50– 70% of all white blood cells (leukocytes). When circulating in the bloodstream and inactivated, neutrophils are spherical. Once activated, they change shape and become more amorphous or amoeba-like and can extend pseudopods as they hunt for antigens. The capacity of neutrophils to engulf bacteria is reduced when simple sugars like glucose, fructose as well as sucrose, honey and orange juice were ingested.
- 22. Neutrophils undergoa process called chemotaxis via amoeboid movement, which allows them to migrate toward sites of infection or inflammation. Cell surface receptors allow neutrophils to detect chemical gradients of molecules such as interleukin-8 (IL-8), interferon gamma (IFN-γ), C3a, C5a, and Leukotriene B4, which these cells use to direct the path of their migration. Neutrophils are phagocytes, capable of ingesting microorganisms or particles. For targets to be recognized, they must be coated in opsonins—a process known as antibody opsonization. They can internalize and kill many microbes, each phagocytic event resulting in the formation of a phagosome into which reactive oxygen species and hydrolytic enzymes are secreted. The consumption of oxygen during the generation of reactive oxygen species has been termed the "respiratory burst", although unrelated to respiration or energy production.
- 23. Eosinophils Eosinophils area type of disease-fighting white blood cell. This condition most often indicates a parasitic infection, an allergic reaction or cancer. High levels of eosinophils in your blood (blood eosinophilia) or in tissues at the site of an infection or inflammation (tissue eosinophilia). This proinflammatory white blood cell generally has a nucleus with two lobes (bilobed) and cytoplasm filled with 200 large granules containing enzymes and proteins with different functions. It stain with acidic dye eosin-Red. They are implicated in numerous inflammatory processes, especially allergic disorders. In addition, eosinophils may have a physiological role in organ formation (e. g. postgestational mammary gland development). Eosinophilic functions include: movement to inflamed areas, trapping substances, killing cells, anti-parasitic and bactericidal activity, participating in immediate allergic reactions, and modulating inflammatory responses.
- 25. Basophils Basophils area type of white blood cell called a granulocyte. There are other forms of granulocyte, such as neutrophils and eosinophils. Granulocyte cells contain granules, which they use to secrete important substances. The granules inside basophils contain heparin, histamine, and other molecules that play a role in inflammation. Basophils are necessary for the immune system’s natural response to invaders, such as infectious germs. When responding to an allergen, basophils that sustain damage will release histamine, which is partially responsible for inflammation during an allergic reaction. Additionally, basophils play an integral role in preventing blood clotting. The heparin inside the cells is a form of natural blood thinner that helps keep the blood flowing through the body. It stain with basic dye methylene blue.
- 26.
- 27. Mast cell Mastcell, tissue cell of the immune system of vertebrate animals. Mast cells mediate inflammatory responses such as hypersensitivity and allergic reactions. They are scattered throughout the connective tissues of the body, especially beneath the surface of the skin, near blood vessels and lymphatic vessels, within nerves, throughout the respiratory system, and in the digestive and urinary tracts. Mast cells store a number of different chemical mediators— including histamine, interleukins, proteoglycans (e.g., heparin), and various enzymes—in coarse granules found throughout the cytoplasm of the cell. Upon stimulation by an allergen, the mast cells release the contents of their granules (a process called degranulation) into the surrounding tissues. The chemical mediators produce local responses characteristic of an allergic reaction, such as increased permeability of blood vessels (i.e., inflammation and swelling), contraction of smooth muscles, and increased mucus production.
- 29. Dendritic cells Dendriticcells (DCs) are antigen-presenting cells of the mammalian immune system. Dendritic cells are a type of antigen-presenting cell (APC) that form an important role in the adaptive immune system. Their main function is to process antigen material and present it on the cell surface to the T cells of the immune system. They act as messengers between the innate and the adaptive immune systems. Dendritic cells are found in tissue that has contact with the outside environment such as the over the skin (present as Langerhans cells) and in the linings of the nose, lungs, stomach and intestines, mucose, skin, lymph tissue. Immature forms are also found in the blood. Dendritic cells also contribute to the function of B cells and help maintain their immune memory. Dendritic producing cytokines and other factors that promote B cell activation and differentiation.
- 31.