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T cells contribute to immune defenses in two major ways: some direct and regulate immune responses; others directly attack infected or cancerous cells. [ 7 ] CD4+ lymphocytes, also called "helper" T cells, are immune response mediators, and play an important role in establishing and maximizing the capabilities of the acquired immune response. [ 3 ]
An immune response is a physiological reaction which occurs within an organism in the context of inflammation for the purpose of defending against exogenous factors. These include a wide variety of different toxins, viruses, intra- and extracellular bacteria, protozoa, helminths, and fungi which could cause serious problems to the health of the host organism if not cleared from the body.
The adaptive immune system evolved in early vertebrates and allows for a stronger immune response as well as immunological memory, where each pathogen is "remembered" by a signature antigen. [55] The adaptive immune response is antigen-specific and requires the recognition of specific "non-self" antigens during a process called antigen ...
There are two categories to which parts of the immune system are assigned: the non-specific, or innate immune system and the adaptive immune system. The non-specific response is a generalized response to pathogen infections involving the use of several white blood cells and plasma proteins. Non-specific immunity, or innate immunity, is the ...
The immune response to cancer can be categorized into the two main categories as discussed above: innate immunity and adaptive immunity. Innate immunity is the first line of defense against cancer. It consists of non-specific immune cells that can recognize and destroy abnormal cells, including cancer cells.
Antigen-presenting cells are vital for effective adaptive immune response, as the functioning of both cytotoxic and helper T cells is dependent on APCs. Antigen presentation allows for specificity of adaptive immunity and can contribute to immune responses against both intracellular and extracellular pathogens.
Both GALT and mesenteric lymph nodes are sites where the immune response is started due to the presence of immune cells through the epithelial cells and the lamina propria. The GALT also includes the Peyer's patches of the small intestine, isolated lymphoid follicles present throughout the intestine, and the appendix in humans. [2]
Unlike CD8 + killer T cells, the CD4 + helper T (T H) cells function by further activating memory B cells and cytotoxic T cells, which leads to a larger immune response. The specific adaptive immune response regulated by the T H cell depends on its subtype (such as T-helper1, T-helper2, T-helper17, regulatory T-cell), [4] which is distinguished ...