By definition immune system is a collection of cells organs and proteins that work together to identify pathogens and enlist/initiate mechanism of eliminating them. When the body discovers foreign substance (antigens) such as bacteria, virus, pathogenic fungi several kinds of cells go to action in what is called an immune response.
Immune responses are a set of adaptive/flexible process that enable the individual organisms to produce variety of specifically reactive proteins and cells that can recognize and cause destruction of an almost infinite variety of foreign invaders. The immune response is divided into two stages.
Recognition; the immune system is able to recognize slightly chemical difference that distinguish one foreign pathogen from another, it is also to discriminate between foreign molecules and the body’s own cells and proteins.
Response; the immune system employs a variety of cells and molecules to make up an appropriate response called an effector response to eliminate and neutralize the pathogenic organisms. Later exposure to the same foreign organism induce a memory response that is characterized by a more fast and heightened immune reaction that saves to eliminate the pathogen before it causes he infections that means if prevents a disease.
The immune system of the body involve different types of cells to induce effective immune response against invaders which include, lymphocytes, macrophages, dendritic cells, granulocyte/white blood cells. Lymphocytes; are one of the any types of white blood cells produced in the bone marrow by the process called hematopoiesis. They produce and display antigen binding cell surface, receptors and therefore mediate the defining immunologic qualities of specificity, diversity memory and self non self recognition.
The body reaction to the antigenic challenges is the immune response in which physiologic and biochemical interactions cause maturation and activation of two types of lymphocytes which are B-lymphocyte (B-cell, T-lymphocyte (T-cells) which act in different ways to recognize and destroy specific at antigens.
Recognition; the immune system is able to recognize slightly chemical difference that distinguish one foreign pathogen from another, it is also to discriminate between foreign molecules and the body’s own cells and proteins.
Response; the immune system employs a variety of cells and molecules to make up an appropriate response called an effector response to eliminate and neutralize the pathogenic organisms. Later exposure to the same foreign organism induce a memory response that is characterized by a more fast and heightened immune reaction that saves to eliminate the pathogen before it causes he infections that means if prevents a disease.
The immune system of the body involve different types of cells to induce effective immune response against invaders which include, lymphocytes, macrophages, dendritic cells, granulocyte/white blood cells. Lymphocytes; are one of the any types of white blood cells produced in the bone marrow by the process called hematopoiesis. They produce and display antigen binding cell surface, receptors and therefore mediate the defining immunologic qualities of specificity, diversity memory and self non self recognition.
The body reaction to the antigenic challenges is the immune response in which physiologic and biochemical interactions cause maturation and activation of two types of lymphocytes which are B-lymphocyte (B-cell, T-lymphocyte (T-cells) which act in different ways to recognize and destroy specific at antigens.
B-lymphocytes
They are produced in and matured within the bone morrow; leave expression unique antigen binding receptor on their membrane called antibody molecules that are glycoprotein in nature. When a naïve B-cell first encounters the antigen that matches its membrane bond antibody, the binding of the antigen to the antibody causes the cell to divide rapidly; its progeny differentiate into memory B-cells and effector B-cells called plasma.
They are produced in and matured within the bone morrow; leave expression unique antigen binding receptor on their membrane called antibody molecules that are glycoprotein in nature. When a naïve B-cell first encounters the antigen that matches its membrane bond antibody, the binding of the antigen to the antibody causes the cell to divide rapidly; its progeny differentiate into memory B-cells and effector B-cells called plasma.
Structure of B-lymphocytic cell
Plasma cells produce the antibody a form that can be secreted and have little or no membrane bound antibody. Plasma cells live for only a few days but secret enormous amount of antibody during this time.
T- Lymphocytes (T-cells)
Lymphocytes destined to become T-cells journery through the thymus where, under the pressure and guidance of the thymic hormones and without the presence of antigen they are driven to proliferate and simultaneously become able to recognize the diversity of antigens the host will encounter throughout life. They exit the thymus as antigenically committed immune competent. Mature T cell, these T-cells produce plasma membrane receptors that are not antibody but are not antibody but are related molecules with similar specificity for antigens, the thymus, which atrophies at puberty and practically disappear in adulthood, consists of a cortex and a medulla interspersed with connective tissue.
There are five types of mature. T-cells each with a different immune function. Memory cells induce the secondary immune response lymphokine-producing cells transfer delayed hypersensitivity (Td) and secreted as macrophages cytotoxic (Tc) cells attack antigens directly and destroy cells that bear foreign antigen and helper T (Th) and suppressor T ( Ts) cells control both cell-mediated and humoral processes the Td and Ts cell phenotypes are probably subsets of Th cells that produce the appropriate lymphokines for activating macrophages or for suppressing other Th cells functions but do not provide any other helper junction.
There are two main types of T-cells (T-lymphocyte)
T-helper cells (TH)
T-cytotoxic cells (TC)
T-helper cells (TH)
Also known as CD4 cells are a types of T-cell that play on important role in the immune system particularly in adaptive immune system.CD4 are glycoproteins found on the surface of T-helper cells
They help activities of other immune cells by releasing T-cells cytokines. These cells help suppress or regulate immune responses. They are essential in B-cell antibody class switching in the activation and growth of cytotoxic T-cells and is maximizing bactericidal activity of phagocytes such as macrophages.
T-helper cell antigen recognition. T-helper cell recognized and interact with an antigens presented to it by major histocompatibility class II complex molecule (MHC class II)
After TH cells recognize and interact with an antigen-MHC class II molecule complex, the cell is activated it become an effector cell that secrets various growth factors collectively known as lymphokines.
The secreted lymphokines play on important role in activating macrophages, B-cells, T-c cells together with other various cells that are involved or participate in the immune responses.
The cytokines derived from activated TH cells cause Tc-lymphocytes that recognize an antigen MH class I molecules complex to proliferates and differentiate into an effector cells.
T-cytotoxic cell (Tc)
Tc is a T-lymphocyte that is type of white blood cell that kills cancer cell that are infected particularly with virus or cell that demaged in other ways.
They are also known as Tc, cytotoxic T lymphocyte (CTC), T-killer cells, cytolytic T-cells, CD8. They are known as CD8 because its (CD8) glycoprotein’s found on surface of TC – cells.
The Tc-cell recognizes antigen presenting to them by major histocompatibility class II protein molecule complex
T-cytotoxic cell antigen recognition under the influence of TH derived cytokines, a Tc-cel that recognizes an antigen presented by MHC class I molecule complex proliferates and differentiate into an infector cells called a cytotoxic T lymphocyte (CTL).
In contract to the Tc cells, the CTL generally does not secret many cytokines, instead exhibits cell-killing or cytotoxic activity. A vital function is monitoring the cells of the body and eliminating any that display antigen such as viral-infected cells, tumor cells and cell of a foreign tissues graft.
ANTIGEN PRESENTING CELLS
These are those cells of the immune system that recognize foreign invaders, react with them and present them to the lymphocytes for recognition.
For the sake of specificity recognition and differentiation of self from non-self, the lymphocytes especially T-lymphocytes recognize and react only to antigens that are mixed and presented by molecules known as major histocompatibility complex protein (MHC).
MHC are sets of cell surface protein that play a vital role of antigen recognition in vertebrate acquired immune system.
They determine the extent of compatibility of tissues hence the name histocompatibility.
There are two classes/kinds of MHC molecules.
MHC I class: are glycoprotein present on almost every cell in the body and acting to present endogenous antigen that originate from the cytoplasm.
The antigens includes; self altered proteins and viral proteins.
MHC class II: are glycoproteins present on specialized antigen presenting immune cells such as macrophages, dendritc cells, and B-cells that produce antibodies. MHC II protein present exogenous antigen that originate extra cellular from foreign bodies such as bacteria.
The tissue are often said to be compatible if they share similar alleles or set of genes referred to human leucocyte antigens (HLA). HLA are the same genes encoding for MHC protein in human.
MHC I class: are glycoprotein present on almost every cell in the body and acting to present endogenous antigen that originate from the cytoplasm.
The antigens includes; self altered proteins and viral proteins.
MHC class II: are glycoproteins present on specialized antigen presenting immune cells such as macrophages, dendritc cells, and B-cells that produce antibodies. MHC II protein present exogenous antigen that originate extra cellular from foreign bodies such as bacteria.
The tissue are often said to be compatible if they share similar alleles or set of genes referred to human leucocyte antigens (HLA). HLA are the same genes encoding for MHC protein in human.
Dendritic cells
Dendritic cells are a type of antigen cell (APC) if the mammalian system that forms an important role in adaptive immune system the main function of dendritic cells is to present antigens and the cells are therefore sometime referred to as professional APCs.
They have the capacity to induce a primary immune response in the inactive or restiry naive T lymphocyte. To do this the dendrite cells capture the antigen from invading bodies which they process and present on their cell surface and presented along with the necessary accessory or co-stimulation molecules.
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-cells activation and differentiation. After an initial antibody response has occurred due to an invading body dendritic cells found the germinal centre of lymphnodes seem to contribute to B-cell memory by forming numerous antibody-antigen complexes. This is to provide a long lasting source of antigen that the B-cells can take up themselves and present to T-cells.
Location of dendritic cells
Dendritic cells are found in tissue that has contact with the outside environment such as the over the sky (present as langerhans cells) and in the linings of the nose, lungs, stomach and the intestines. Immature forms are also found in the blood. Once activated, dendrites cells move to the lymph tissue to interact with to interact with T cells and B-cells and help shape the adaptive immune response. During development, they develop branched projections called “dendrites” which is why the cell are so named.
Dendritic cells are a type of antigen cell (APC) if the mammalian system that forms an important role in adaptive immune system the main function of dendritic cells is to present antigens and the cells are therefore sometime referred to as professional APCs.
They have the capacity to induce a primary immune response in the inactive or restiry naive T lymphocyte. To do this the dendrite cells capture the antigen from invading bodies which they process and present on their cell surface and presented along with the necessary accessory or co-stimulation molecules.
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-cells activation and differentiation. After an initial antibody response has occurred due to an invading body dendritic cells found the germinal centre of lymphnodes seem to contribute to B-cell memory by forming numerous antibody-antigen complexes. This is to provide a long lasting source of antigen that the B-cells can take up themselves and present to T-cells.
Location of dendritic cells
Dendritic cells are found in tissue that has contact with the outside environment such as the over the sky (present as langerhans cells) and in the linings of the nose, lungs, stomach and the intestines. Immature forms are also found in the blood. Once activated, dendrites cells move to the lymph tissue to interact with to interact with T cells and B-cells and help shape the adaptive immune response. During development, they develop branched projections called “dendrites” which is why the cell are so named.
Macrophages
Macrophages are a type of white blood cell of the immune system that engulfs and digests cellular debris, foreign substance, microbes, cancer cells, and anything else that does not have the type of proteins specific to health body cells on its surface in a process called phagocytosis.
Formation of macrophages
Macrophages are formed through differentiation of mancytes, one of the major group of white blood cells of the immune systems.
Mechanism of antigen elimination
When there is tissue damage or infection the monocytes leave the blood stream and enter the affected tissue or organ and undergo a series of changes to become macrophages.
These macrophages can modify themselves to form different structure in order to fight various different microbes and invaders.
In this way macrophages provide a first line of defense in protecting the host from the infection.
This type of immunity is a long-term immunity which is acquired when a macrophage digests a microbe and presents the microbe antigen on its surface to alert other white blood cells to presence of the invading particle. Other white blood cells they multiply and amount an immune response against the pathogen.
The pathogen, displaying the antigen can be recognized and targeted directly by antibodies should future re-infection occur, meaning that the pathogen is in a sense “remember” by the immune system.
Each of the macrophages have specific protein markers on their surfaces. Some examples include CD15, CD11b, CD68, lysozyme M etc.
Macrophages are a type of white blood cell of the immune system that engulfs and digests cellular debris, foreign substance, microbes, cancer cells, and anything else that does not have the type of proteins specific to health body cells on its surface in a process called phagocytosis.
Formation of macrophages
Macrophages are formed through differentiation of mancytes, one of the major group of white blood cells of the immune systems.
Mechanism of antigen elimination
When there is tissue damage or infection the monocytes leave the blood stream and enter the affected tissue or organ and undergo a series of changes to become macrophages.
These macrophages can modify themselves to form different structure in order to fight various different microbes and invaders.
In this way macrophages provide a first line of defense in protecting the host from the infection.
This type of immunity is a long-term immunity which is acquired when a macrophage digests a microbe and presents the microbe antigen on its surface to alert other white blood cells to presence of the invading particle. Other white blood cells they multiply and amount an immune response against the pathogen.
The pathogen, displaying the antigen can be recognized and targeted directly by antibodies should future re-infection occur, meaning that the pathogen is in a sense “remember” by the immune system.
Each of the macrophages have specific protein markers on their surfaces. Some examples include CD15, CD11b, CD68, lysozyme M etc.
Granulocyte
Granulocytes are a type of white blood cell that has small granules which contain proteins.
Granulocytes are a type of white blood cell that has small granules which contain proteins.
The specific types of granulocytes are;
(i) Neutrophils,
(i) Neutrophils,
(ii) Eosinophils and
(iii) Basophils
Granulocytes, specifically neutrophils, help the body fight bacteria infection. The number of granulocytes in the body usually increases when there is a serious infection people with a lower number of granulocytes are more likely to develop bad infection more often.
Neutrophils
Is the major constitute of circulating white blood cells (leukocytes) (constitute about 50%-70%).
After differentiation in the bone marrow neutrophils are released into the peripheral blood and circulate for 7 to 10 hours before migrating into the tissue, where they have a life span of only a few days.
In response to many types of infection the numbers of circulating neutrophils increase significantly and more are recanted to tissues.
The resulting transient increase in the number of circulating neutrophils, called leukocytosis is used medically as an indication of infection.
Basophils
Basopils are non-phagocytic granulocytes that contain large granules filled with basophilic protein.
In response to infection (of parasitic origin) basophils release the contents of their granules i.e. histamine that mediate inflammatory response or allergy reactions.
Eusinophils
They play their most important role in the defaure against multicellular organisms.
They secret cytokines that regulate B and T lymphocytes, there by influencing the adaptive immune response.
Granulocytes, specifically neutrophils, help the body fight bacteria infection. The number of granulocytes in the body usually increases when there is a serious infection people with a lower number of granulocytes are more likely to develop bad infection more often.
Neutrophils
Is the major constitute of circulating white blood cells (leukocytes) (constitute about 50%-70%).
After differentiation in the bone marrow neutrophils are released into the peripheral blood and circulate for 7 to 10 hours before migrating into the tissue, where they have a life span of only a few days.
In response to many types of infection the numbers of circulating neutrophils increase significantly and more are recanted to tissues.
The resulting transient increase in the number of circulating neutrophils, called leukocytosis is used medically as an indication of infection.
Basophils
Basopils are non-phagocytic granulocytes that contain large granules filled with basophilic protein.
In response to infection (of parasitic origin) basophils release the contents of their granules i.e. histamine that mediate inflammatory response or allergy reactions.
Eusinophils
They play their most important role in the defaure against multicellular organisms.
They secret cytokines that regulate B and T lymphocytes, there by influencing the adaptive immune response.
Mast cells
They are also known as Mastocytes or labrocytes.
They are found in tissue like skin, connective tissue of various organs and mucosal epithelial tissue of the respiratory genitourinary and digestive traits.
They posses large number of grants that contain histamine and other phamacological active substances.
They play vital in the development of allergies.
They are also known as Mastocytes or labrocytes.
They are found in tissue like skin, connective tissue of various organs and mucosal epithelial tissue of the respiratory genitourinary and digestive traits.
They posses large number of grants that contain histamine and other phamacological active substances.
They play vital in the development of allergies.
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