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The ability of the immune system to respond to pathogens is diminished in both the young and the elderly, with immune responses beginning to decline at around 50 years of age due to immunosenescence. [ 112 ] [ 113 ] In developed countries , obesity , alcoholism , and drug use are common causes of poor immune function, while malnutrition is the ...
According to this theory, the chief cell of the immune system is the B cell, activated by recognizing non-self structures. Later research showed that B cell activation is reliant on CD4+ T helper cells and a co-stimulatory signal from an antigen-presenting cell (APC).
The original antigenic sin: When the body first encounters an infection it produces effective antibodies against its dominant antigens and thus eliminates the infection. But when it encounters the same infection, at a later evolved stage, with a new dominant antigen, with the original antigen now being recessive, the immune system will still produce the former antibodies against this old "now ...
The following outline is provided as an overview of and topical guide to immunology: . Immunology – study of all aspects of the immune system in all organisms. [1] It deals with the physiological functioning of the immune system in states of both health and disease; malfunctions of the immune system in immunological disorders (autoimmune diseases, hypersensitivities, immune deficiency ...
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;
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.
The immune system extends this response to its treatments of self-antigens, softening reactions against allergens, the body, [9] and digestive microorganisms. [15] As the worms developed ways of triggering a beneficial immune response, humans came to rely on parasitic interaction to help regulate their immune systems.
The immune system may respond in multiple ways to an antigen; a key feature of this response is the production of antibodies by B cells (or B lymphocytes) involving an arm of the immune system known as humoral immunity. The antibodies are soluble and do not require direct cell-to-cell contact between the pathogen and the B-cell to function.