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This cytokine—a class of signaling molecule [39] —kills cancer cells and cells infected by viruses, and helps to activate the other cells of the immune system. [ 40 ] In some diseases, e.g., the rare chronic granulomatous disease , the efficiency of phagocytes is impaired, and recurrent bacterial infections are a problem. [ 41 ]
Each antibody binds to a specific antigen in a highly specific interaction analogous to a lock and key.. An antibody (Ab) or immunoglobulin (Ig) is a large, Y-shaped protein belonging to the immunoglobulin superfamily which is used by the immune system to identify and neutralize antigens such as bacteria and viruses, including those that cause disease.
Bacteria, dead tissue cells, and small mineral particles are all examples of objects that may be phagocytized. Some protozoa use phagocytosis as means to obtain nutrients. Where phagocytosis is used as a means of feeding and provides the organism part or all of its nourishment, it is called phagotrophy and is distinguished from osmotrophy ...
It detects and responds to a wide variety of pathogens, from viruses to bacteria, as well as cancer cells, parasitic worms, and also objects such as wood splinters, distinguishing them from the organism's own healthy tissue. Many species have two major subsystems of the immune system.
Serum substances that aggregate bacteria and precipitate bacterial toxins: von Gruber and Durham (1896), Kraus (1897) Hemolysins: Serum substances that work with complements to lyse red blood cells: Jules Bordet (1899) Opsonins: Serum substances that coat the outer membrane of foreign substances and enhance the rate of phagocytosis by macrophages
Macrophages (/ ˈ m æ k r oʊ f eɪ dʒ /; abbreviated Mφ, MΦ or MP) are a type of white blood cell of the innate immune system that engulf and digest pathogens, such as cancer cells, microbes, cellular debris and foreign substances, which do not have proteins that are specific to healthy body cells on their surface.
Cellular immunity protects the body through: T-cell mediated immunity or T-cell immunity: activating antigen-specific cytotoxic T cells that are able to induce apoptosis in body cells displaying epitopes of foreign antigen on their surface, such as virus-infected cells, cells with intracellular bacteria, and cancer cells displaying tumor antigens;
Glycocalyx is produced by many bacteria to surround their cells, [89] and varies in structural complexity: ranging from a disorganised slime layer of extracellular polymeric substances to a highly structured capsule. These structures can protect cells from engulfment by eukaryotic cells such as macrophages (part of the human immune system). [90]